Implied Volatility: Reading It in Points, Against Recent Days and Against Its Year

What Implied Volatility Is

What is implied volatility, and what will this page not tell me?

Implied volatility, written IV, is not observed. It is solved for: the pricing model is run backwards from an option’s traded price until it returns the volatility that gives that price. A reading of 11.84% means that, with this strike, this expiry and this level of the underlying, the traded prices are consistent with a yearly volatility of 11.84%. The number is easy to find on any option chain and hard to use, because nobody can see a percentage in a chart of the index.

This page therefore does two things with it. It turns the percentage into points, the unit of the index you already watch: how far the underlying can travel, by expiry and in one session, at the size the option prices are paying for. And it puts the reading next to two comparisons: the days the underlying has actually had, and the reading’s own past year. Nothing on the page says which way the price will go. IV can rise in a falling market and in a rising one, because both are movement, which is why the page never colours an IV level.

Where the Numbers Come From

• Today’s readings. The page solves IV afresh from the traded premiums of the Call and the Put at each strike, in the one-minute snapshots collected for the day. It does not read the IV stored in the files, because most day files hold a zero there. A minute whose prices do not give an IV is left out of the line, never drawn as zero.
• The other expiries. The option chains of the next live expiries are read when the page opens and then at most once a minute (3 expiries at most), and only when a new reading has arrived.
• The underlying’s daily closes. The last 20 sessions give the actual day. The page asks for about a year of daily closes, once.
• The year of 30-day IV. A file of daily closes built from NSE’s F&O closing prices (the bhavcopy). On the live page it now runs from 15 September 2025 to 16 October 2026, 270 sessions (not rebuilt by us). The Options Scanner ranks the same file.
• India VIX. For NIFTY only, read at most once a minute.
• How fresh. The chain pages re-fetch about every 5 seconds while the market is open. This page works from the one-minute archive and says the time of its newest reading in the insight row. This page does not use Open Interest at all: it reads traded premiums.

Read an IV Reading in Two Minutes

What do I read first, and in what order, to know whether option prices are dear or cheap right now?

The first time, the page opens on NIFTY, its nearest expiry and the Intraday view; after that it reopens on the view you left. The insight row, and the detail panel behind it, give four answers above every view. They are in a fixed order, and so is the way to read them: first how big a move the option prices are paying for, in points; then whether that is more or less than the days the market has really had; then where today’s level sits in its own past year; and last how the level moved today. The six steps below take about two minutes. The page places no order at any step.

1. Open the page and read the insight row

   Open Implied Volatility. Under the page bar you see a thin insight row: the verdict in words, the at-the-money IV, its three small changes and one short line of the priced move. Under it the chart of the view you chose runs to the bottom of the window. On a phone the same row sits above the chart, and the Intraday and History charts fill the rest of the screen (see Reading it on a phone).

   Real tool · illustrative dataThe page as it opens: the bar, the insight row and the Intraday chartSwipe sideways to see all of itEnlarge

   

   Close

   

2. Open the insight: the four answers in four lines

   Real tool · illustrative dataThe opened insight, in the order to read itSwipe sideways to see all of itEnlarge

   

   Close

   

   Press the arrow at the end of the insight row. The first line reads ±378 pts (1.54%) by expiry, with the range 24135 – 24890 in the detail panel. That is the move the option prices are paying for by expiry, one standard deviation either side of spot. It names no direction. The reason for this figure is in The priced move in points.

3. Read the third line: dear or cheap against recent days

   The line Options are priced for days 1.29× the size of NIFTY’s typical recent day sets the priced move per day, ±198 pts, against the underlying’s actual days over the last 20 sessions, ±154 pts. Options priced for bigger days than the market has been having are dear against recent history; smaller, cheap. The rule is in Per day, and against actual days.

4. Read the second line: high or low against its own year

   The line The 30-day IV is above 65% of its last 252 daily closes is the IV Percentile, IVP 65; the detail panel adds IV Rank 29. At 80 or more the verdict reads High IV, at 20 or less Low IV, and between them Normal IV. See Against its year.

5. See how it moved today

   The insight row carries three small changes: 5m, 15m and Today. On the picture they read −0.07 pts, −0.06 pts and −0.24 pts. Open the insight for the verdict in words and the working behind every figure (The insight row).

6. Open the view that answers your next question

   Intraday shows IV through today (its chart is titled ATM IV today). Strikes shows IV at each strike (IV by strike). Expiries puts the live expiries side by side (Compare expiries). History shows the past year (30-day IV history). A short guide to choosing is in The screen at a glance.

The Screen at a Glance

What is on the screen, and which part do I read first?

The page is one column, top to bottom, and the order is the order of reading. One part sits above every view and never changes with it: the insight row, which opens into the four answers. Under it is one card for the view you chose, which on a desktop runs to the bottom of the window. Choosing a view changes only that card.

• Page barThe four views Intraday, Strikes, Expiries and History, and Customise (on the Expiries view the expiry selector stands in its place).
• Insight rowThe verdict in words, the at-the-money IV, the 5m, 15m and Today change, one short line of the priced move, the time of the data, and an arrow that opens it.
• Four answersOpened from the arrow at the end of the row: the priced move to expiry, where the 30-day IV sits in its year, the priced day against actual days, and how today ranged. The detail panel works each one out.
• The view cardOne chart or table, with a short title: ATM IV today, IV by strike, Compare expiries or 30-day IV history. On a desktop its key sits in the card head and nothing sits under the chart; the Strikes and History views continue below with four figures, and Intraday with the straddle split.

Real tool · illustrative dataThe page barSwipe sideways to see all of itEnlarge

Close

Three words on the screen are worth knowing now. 1 SD is one standard deviation, the size of the priced move. ATM IV is the IV at the forward, the centre of the option prices. IVP is IV Percentile. Each is defined in the Glossary and in the part that uses it.

A

Part A of 6 The four answers How big a move is priced, in points; dear or cheap against recent days; high or low against its own year. 4 topics

The question each topic answers

1. What is the at-the-money IV, how is it measured, and when does the page refuse to give one?
2. How many index points is the market paying for, and how is the percentage turned into them?
3. Is one day of this expiry priced above or below the days the underlying has really had?
4. Is today’s level high or low for this underlying, measured against its own past year?

Answer One: the At-the-money IV

What is the at-the-money IV, how is it measured, and when does the page refuse to give one?

Real tool · illustrative dataThe reading: six tilesEnlarge

Close

The first answer is the at-the-money IV of the expiry the page is reading. It sits in the insight row as the chip ATM IV 11.84%, and the first tiles of The reading in the detail panel give it in full: ATM IV now 11.84%, Since the open −1.00 pts, and Today’s range, where the day’s readings have run from 11.83% to 13.08%. The tile since the open is the latest reading minus the first reading of the session, in IV points (one point is one percentage point of IV). It takes a direction colour only when the change is larger than 0.005 of a point; anything smaller cannot alter a figure printed to two decimals.

Why “at the money” Means the Forward Here

An option is at the money when its strike sits at the centre of the prices. That centre is not spot. It is the forward: where the option prices put the underlying at expiry, which is spot plus the cost of carrying it until then. At 6.5% a year and 30 days the two differ by about half of one per cent, which on NIFTY is more than two strikes. The page works the forward out from the Call and Put prices themselves (put–call parity), so it needs no futures price. On the picture the tile says “At the forward, 24539”: the IV 11.84% read at the forward 24539, while spot is 24512.35. The forward, not spot explains why this matters.

How the Figure Is Measured

1. The page takes the one-minute snapshots of the day for this expiry only. A snapshot of another expiry is left out, so a change of expiry is never shown as a change of IV.
2. It finds the forward, then reads the straddle (the Call plus the Put) at the two strikes either side of it. One IV reprices both legs of a strike, so it inverts the straddle and not the two legs separately.
3. It blends the two strikes to the forward itself, in total variance (IV squared times time), so the line moves smoothly when the price crosses a strike instead of stepping.

Each price is the last traded price of the leg, not the midpoint of bid and ask, and the model is Black–Scholes in its forward form with a fixed 6.5% rate. A leg that barely moves with volatility is not used: a strike whose premium changes by less than ₹0.10 per vol point cannot show an IV, because one tick of ₹0.05 would then move the solved figure by half a vol point or more.

When the Page Gives No Number

The page never shows a zero for a reading it could not make. It names the cause in these exact words:

When some minutes fail and others do not, the opened insight says so in one line: “N of M snapshots gave no reading” with the commonest cause. Those minutes are gaps in the line, never dips to zero.

Answer Two: the Priced Move in Points

How many index points is the market paying for, and how is the percentage turned into them?

Real tool · illustrative dataThe priced range and what the prices pay forEnlarge

Close

Implied volatility is a yearly figure, and almost nobody holds an option for a year. The conversion to the move that matters is one line:

The days left are calendar days from the time of the reading to the close of the option market on the expiry date. From 11:30 on Wednesday 30 September to 15:40 on Tuesday 6 October is 6 days, 4 hours and 10 minutes, which is the 6.174 in the working. (The note printed under this calculation in the detail panel reads “3:40 pm close on expiry (3:30 pm for expiries before 3 Aug 2026)”, which matches the figure. The 15:40 close itself is explained in What we have not verified.) The result, ±378 pts, is 1.54% of spot, and the range 24135 – 24890 is spot less and plus that move (the 1 SD low and the 1 SD high of the priced range). The range is centred on spot, not on the forward.

Why a Square Root

Volatility grows with the square root of time, not with time. Four times the time gives twice the move; nine times the time, three times. A month-out option is therefore not worth four weekly options, and the move to the 27 October expiry, about four times as far away as the 6 October one, is not four times larger. The Expiries view shows it side by side: the move to 13 October is 597 points against 378 to 6 October.

What One Standard Deviation Means

The result is one standard deviation, shown as “1 SD”. The pricing model puts about two outcomes in three inside the range and says nothing about which side. Three cautions belong with it.

• It is a property of the model, not a count of past days. It is what the option prices say, not what happened.
• It is symmetric, and the true distribution is not. It is a good guide near the money and a rougher one in the tails. A move of two standard deviations is not rare enough to ignore.
• It describes the move to expiry. For today, use the per-day figure (answer three).

The Straddle Beside It, and the Option Chain’s Expected Move

The Expiries view prints the price of the at-the-money straddle in its last column, ATM straddle, here ₹301.25, strike 24550 for the 6 Oct row: the Call plus the Put at the strike nearest the forward. One priced move is about 1.25 times the straddle (on the picture 378 against 1.25 × 301.25 = 376.56). The Option Chain and the Straddle page print an “Expected move” of 0.85 times the straddle, here 256.06, which is a narrower band; the chain’s tile reads “0.85 × straddle”. This page’s figure is worked from the IV instead, and the page says so: it is 1 SD, from IV. (The chain’s own “1 SD to expiry” tile, labelled “From ATM IV”, is this same figure.) Both are correct for what they say. They are different bands, so read the basis printed beside each number, not the word “move”. (We have not found a study behind the 0.85; it is the chain’s own convention.)

On the Last Session

When one session or less is left, the whole remaining move belongs to today. The sentence then says This is the last session before expiry, so all of it is today’s, the insight row words the figure as left today, and the calculation is titled Priced move left today (see the expiry-day picture). The move to expiry keeps its title and reads the same.

Answer Three: Per Day, and Against Actual Days

Is one day of this expiry priced above or below the days the underlying has really had?

Real tool · illustrative dataAgainst actual movesEnlarge

Close

This answer is the question a trader brings first: are these options dear or cheap? It does not compare an IV with another IV. It compares one priced day, in points, with one actual day, in points.

The Priced Day

The sessions left are counted on the exchange calendar: the unspent part of today (11:30 to 15:40 is 0.649 of a session) plus every whole session up to and including the expiry. From Wednesday 30 September to Tuesday 6 October these are Thursday 1 October, Monday 5 October and Tuesday 6 October, so 3.649. Friday 2 October is a holiday in the app’s own calendar and the weekend is shut, so none of them is counted (not checked against an exchange calendar). The move per day is ±198 pts, which the insight row also prints beside the move to expiry: “±378 pts to 6 Oct (1.54%) · ±198 pts a day”.

The Actual Day

Historical volatility over 20 sessions is the figure every volatility tool quotes. Twenty sessions is one trading month, long enough to be steady: a standard deviation from 20 returns is uncertain by about 16 per cent, where five returns would be uncertain by about 35. The page converts it to points at today’s spot so that the two days are measured in one unit. It needs 21 daily closes; without them the cell says No daily closes to compare with (and Reading daily closes… while they are still being read).

The Word

The ratio is worked from the whole numbers on screen, so you can redo it with a calculator: 198 divided by 154 is 1.29, at or above the 1.2 line, so the word is bigger. The page names a side only when the gap clears the uncertainty of a 20-session measurement. The sentence describes prices. It does not say what to do, and it compares with the recent past, not with what comes next.

The Previous Close, and Why It Is in Points

The Today section of the detail panel says the priced day has gone from ±204 pts at the previous close to ±198 pts, which is the same priced day worked out at the previous session’s last reading. It is the clock-free way to say whether options got dearer today. IV itself cannot say it: on a Monday it jumps several points above Friday’s close with nothing having happened, because IV counts the weekend’s calendar days and the market does not move on them. Points per session carry no such calendar. The whole of this is in Calendar days.

Real tool · illustrative dataAcross strikes, and TodaySwipe sideways to see all of itEnlarge

Close

On the Last Session

With one session or less left, the figure is titled Priced move left today and is the whole of today’s remaining move. It then shrinks through the afternoon, and set against a whole actual day it will often read smaller. That is the arithmetic of a few hours left, not a cheap market.

Answer Four: Against Its Own Year

Is today’s level high or low for this underlying, measured against its own past year?

Real tool · illustrative dataAgainst its own yearEnlarge

Close

A level means little until it is set against its own history. The page does that with two numbers that traders know by name.

The Words

The verdict in the insight row reads High IV when the printed IV Percentile is 80 or more, Low IV at 20 or less, and Normal IV between (the detail panel prints the same rule under How the verdict is decided). The test is made on the whole number you see, so a printed 80 never reads Normal. IV Percentile leads because it uses every day of the year. IV Rank rests on only two days, the highest and the lowest close, so one spike can hold it down for a whole year.

Why the Year Uses a 30-day IV

The IV of a weekly expiry climbs through every week into expiry and resets after it. A year of those readings would rank the day of the week, not the volatility. So the year is measured on a steady 30-day IV, solved every session from NSE’s F&O closing prices. The rule for today’s figure:

• Leave out any expiry with fewer than 2 days left.
• Blend the nearest expiry on each side of 30 days, linearly in total variance (IV squared times time).
• If no expiry reaches 30 days, the furthest one stands in. If every expiry is past 30 days, the nearest one stands in.
• The furthest expiry must be at least 14 days away. Otherwise there is no 30-day IV.

On the picture the three expiries are “6 Oct 11.84% (6d), 13 Oct 12.82% (13d), 27 Oct 13.29% (27d) → 13.29%”. None reaches 30 days, so the furthest, 27 Oct, stands in and the 30-day IV is its own at-the-money IV, 13.29%. The BANKNIFTY picture lists one expiry, 27 October at 27 days, so it stands in too and the 30-day IV is its own 14.45%. A true blend needs one expiry on each side of 30 days (Expiries).

The Options Scanner ranks the same 30-day IV against the same file, so the two pages print one IV Rank.

How the Year of Closes Is Built

The year is a file of one 30-day IV per session for each NSE F&O underlying. Each value is solved from that session’s closing prices in NSE’s F&O bhavcopy, with the same solve the page runs on today’s prices. The rules:

• Three expiries after the session. Each session reads the underlying’s three nearest expiries that fall after the session date. An expiry that settles on that day is never used, because it has no time left. These are the same three expiries the page tracks once the day’s expiry has settled.
• Expiry days have a reading. Because the settling expiry is skipped, an expiry day (a NIFTY Tuesday, for example) still has an expiry at least 14 days away, and so a value. Earlier builds counted the settling expiry, and those days were empty.
• The same blend. The three expiries are blended to 30 days by the rules above.
• A contract that did not trade has no close, and it is left out.

On the live page the file now runs from 15 September 2025 to 16 October 2026, 270 sessions, and it includes the Sunday Budget session of 1 February 2026. IV Percentile and IV Rank use its last 252 sessions. The History card says how far the file runs (Closes to its last date). We did not rebuild the file ourselves (not verified). The year in this guide’s pictures is invented and ends earlier.

When the History Is Short

Real tool · illustrative dataA short history: 72 sessionsSwipe sideways to see all of itEnlarge

Close

With fewer than 60 closes the page shows neither number. From 60 it shows the percentile, names the window (Only 72 sessions of closes are stored, fewer than a full year) and keeps the rank back until 252 sessions are stored, because a short window has almost certainly not seen a real spike. The History view then reads Needs a full 252 sessions under IV rank.

Real tool · illustrative dataThe History figures with 72 sessionsSwipe sideways to see all of itEnlarge

Close

India VIX, for NIFTY Only

Real tool · illustrative dataThe same answers for BANKNIFTYSwipe sideways to see all of itEnlarge

Close

For NIFTY only, the detail panel’s calculations carry one more line, India VIX 13.41, +0.29 on the day, and the History view can draw it (Customise, History chart, India VIX). It is NSE’s own 30-day index, shown as a yardstick. It is built by a different method from the page’s at-the-money IV, from NIFTY’s near and next month options across all strikes, so, on the page’s own note, it usually reads a little above an at-the-money 30-day IV (not verified). The two are not the same number (why platforms differ).

B

Part B of 6 The insight card The verdict in words, the three small changes, and every figure worked out with its own numbers. 3 topics

The question each topic answers

1. What does the thin row above the chart tell me, and what do its three small changes mean?
2. What does the opened insight add, and what does Measured over choose?
3. Where can I see every figure on the page worked out, step by step?

The Insight Row

What does the thin row above the chart tell me, and what do its three small changes mean?

Real tool · illustrative dataThe insight row, closedSwipe sideways to see all of itEnlarge

Close

The row is built on the app’s shared insight card, with the content of this page. Reading it from the left:

• The verdict in a pill: Normal IV on the picture.
• The chip ATM IV 11.84%: the figure the three changes are measured on.
• 5m, 15m and Today: how far the at-the-money IV has travelled over the last 5 minutes, the last 15 minutes and today. They are the same three windows the Option Chain uses. Today is measured from the previous session’s close; when the archive holds no earlier session the key becomes Since 9:15 am and says where the day started instead.
• A one-line summary of the priced move: the move to expiry, the same move as a share of spot, and the move per day, as in “±378 pts to 6 Oct (1.54%) · ±198 pts a day”. On the last session it reads “±N pts left today” with the range. The note that this is one standard deviation, with no direction, is in the opened box and the detail panel.
• The time of the data, and at the end an arrow that opens the insight.

The Verdict Words

Real tool · illustrative dataNo year to use: the verdict falls backSwipe sideways to see all of itEnlarge

Close

The pill is always in ordinary ink. It names a level, and the page does not colour a level of volatility: IV can rise in a falling market and in a rising one, so green or red would claim a direction the number does not carry. Only the three changes take a direction colour, and only when they clear a floor of 0.005 of a point.

A Change Is Not Zero When It Is Missing

If a window has no matching reading (the session is only a few minutes old, or the nearest snapshot is too far from the target), the page prints a dash and the reason, never “unchanged”. A 5-minute window will take a baseline up to about a minute and a half either side of five minutes earlier, and a 15-minute window two and a half. Beyond that it is reported as missing rather than quietly widened.

The Opened Box and Measured Over

What does the opened insight add, and what does Measured over choose?

Real tool · illustrative dataThe insight, openedSwipe sideways to see all of itEnlarge

Close

The arrow at the end of the row opens it downwards. It holds, in this order:

1. The verdict with the symbol and the expiry under it (“NIFTY · 6 Oct expiry”).
2. Measured over: 5 min, 15 min or Day. It chooses which of the three changes in the row is set in bold. It never changes the verdict, which comes from the year.
3. Four sentences. The priced move (“priced for a move of ±378 pts by expiry, one standard deviation from IV, with no direction”); the year (“The 30-day IV is above 65% of its last 252 daily closes”); the priced days against the actual days (“Options are priced for days 1.29× the size of NIFTY’s typical recent day”); and today’s range (“ranged from 11.83% to 13.08%”). Figures come first and are in bold. A sentence whose figure cannot be formed is left out, never printed as zero.
4. The note. One short note at the right. It always says that IV counts calendar days; it adds how many snapshots gave no reading when some did not, and a note when more strikes started trading during the day or when snapshots of another expiry were left out.
5. The time of the data, the number of one-minute readings today and the expiry, a small status label (Live updates while the card follows the newest reading, Saved reading when it does not; not tested), and the button Full detail and calculations. The label is not a promise of a continuous stream: the page works from the one-minute archive, so read the time of the data.

On a phone the box opens as a sheet over the page with a scrim, and a close button; Escape closes it on a keyboard and returns focus to the button that opened it.

The Changes, and the Shut Days

The three changes sit in the row: 5m, 15m and Today. With 15 min chosen the 15m change is in bold, here “11.84% at 11:30 am − 11.90% at 11:15 am = −0.06 pts” in the detail panel. Choose Day and the bold one is Today, whose baseline is the previous session’s close. After a holiday or a weekend part of that change is the calendar and not the market, and the note at the right of the box says so every time: IV counts calendar days to expiry, so it jumps after shut days with nothing having happened, and the priced move in points does not.

Real tool · illustrative dataDay chosen, on a Monday after a holiday weekendSwipe sideways to see all of itEnlarge

Close

The date of the data is the date of the newest reading in the archive, not the clock of your device. Trust that time over any other label on the box.

The Detail Panel and Every Calculation

Where can I see every figure on the page worked out, step by step?

Real tool · illustrative dataFull detail and calculations, the topSwipe sideways to see all of itEnlarge

Close

The button Full detail and calculations opens a side panel. Its job is to let you check every figure on the page. Its sections, in order:

1. How the verdict is decided. Three steps: the year (IV Percentile with its rule, 80 or more reads High and 20 or less reads Low), the priced day against the actual day, and the result. The middle step decides only when the year is missing.
2. The reading. Six tiles: ATM IV now (with the forward it was read at), since the open (with the opening time), today’s range (with the times of the high and the low), 1 SD to expiry, IV Percentile and IV Rank.
3. The priced range. A short ladder: 1 SD high, the price, 1 SD low, each with its distance in points and per cent.
4. Each answer in full. What the prices pay for, against actual moves, against its own year, across strikes, and today.
5. How each figure is worked out, below.
6. 5 min, 15 min and Today, with the two snapshots each change was taken between, for example “11.84% at 11:30 am − 11.91% at 11:25 am = −0.07 pts”.
7. What this reading cannot see, and a short technical method: three steps of how the at-the-money IV is built.

Real tool · illustrative dataThe panel at How each figure is worked out, unfoldedSwipe sideways to see all of itEnlarge

Close

The Ten Calculations

Every working line is checked by the page’s own tests: each one redoes to the figure it prints. If you ever find a printed figure you cannot reproduce from its line, that is a fault worth reporting. A note under India VIX says it usually reads about a point above an at-the-money 30-day IV, because out-of-the-money Puts carry more IV; this is the page’s own statement and we have not checked it against NSE’s method (What we have not verified).

C

Part C of 6 The four views Intraday, Strikes, Expiries and History: one chart or table for each question. 5 topics

The question each topic answers

1. How has the at-the-money IV moved through today, and against what price?
2. The straddle is down. Was it time, did IV come off, or did the price move?
3. Which strikes cost more in IV, and how has the curve moved since the open?
4. Which expiry is paying for the most movement each day, and what is the 30-day IV?
5. Is today’s IV high or low for the past year, and has it run above or below the moves the market actually made?

Intraday: the At-the-money IV Through Today

How has the at-the-money IV moved through today, and against what price?

Real tool · illustrative dataThe Intraday viewSwipe sideways to see all of itEnlarge

Close

This is the view the page opens on the first time. The card is titled ATM IV today. It is built from the one-minute readings of the day, from the open to the latest, grouped into steps that you choose with the interval tabs (5 minutes at first). The chart is one line: the IV, in plain ink, on the right axis, in per cent to two decimals, with its latest value tagged on that axis. The spot of the underlying is dashed and uses the left axis, so you can see what the IV moved against. Two dashed rules mark the day’s highest and lowest IV, tagged Day high and Day low. The key sits in the head of the card (ATM IV, NIFTY spot, Day high / low), and nothing sits under the chart on a desktop. A phone adds the scope line under the plot, 6 Oct expiry · 30 Sep session; the detail panel counts the readings, 136 one-minute readings today.

How the Line Is Built

• One expiry and one session. Snapshots of another expiry, or of an earlier day, are left out. Without that rule the line would splice yesterday’s close in front of today’s open.
• Absent is not zero. A minute that gave no reading is a gap. The count of such minutes appears in the opened insight.
• At most 400 readings are drawn; if there were more, the oldest are thinned first, so the newest reading is never dropped.
• A reading needs two points to draw. With one reading the verdict says First reading (states).

The Chart’s Own Tools

Real tool · illustrative dataThe chart toolsSwipe sideways to see all of itEnlarge

Close

The chart is kept simple, as on the PCR and Straddle pages. The row above it carries only three things: the interval as plain text tabs (1m, 3m, 5m, 15m, 30m, 1h, 1D), a crosshair switch and full screen. There are no indicators, no chart types, no chart settings and no drawing tools. The interval changes how many readings are drawn. It does not change the readings. The camera row under the chart zooms and moves along the time axis.

Real tool · illustrative dataHovering a pointSwipe sideways to see all of itEnlarge

Close

Reading It Without Fooling Yourself

• A falling IV line on a quiet day is often the calendar. IV is annualised over calendar days, so on the last days of a weekly expiry it can slide through the session with the market unchanged (Calendar days).
• A rising line is not bullish and a falling line is not bearish. It says options got dearer or cheaper, whichever way the price went.
• Check the left axis before you link the two lines. Spot may have moved only a few points over the day.

Real tool · illustrative dataBoth extra lines offSwipe sideways to see all of itEnlarge

Close

Where the Straddle’s Price Change Came From

The straddle is down. Was it time, did IV come off, or did the price move?

Real tool · illustrative dataThe split of the straddle’s changeSwipe sideways to see all of itEnlarge

Close

Under the Intraday chart, once there are two readings, a card answers the question sellers and buyers ask every afternoon: the straddle is down; was that time, or did IV come off? A premium chart alone cannot say. The card, titled What moved the 24550 straddle, starts from the at-the-money straddle at the strike nearest the forward, 24550, and compares its price at the day’s first reading and now: Call + Put ₹333.00 → ₹301.25, a change of −₹31.75.

The four parts add up to the change exactly (−8.62 − 24.33 − 2.41 + 3.61 = −31.75), because the last row is whatever is left. The Call and the Put at one strike are split separately and then added part by part. A straddle barely cares which way the price went, since its Delta is near zero, so what remains is mostly IV and time: the two things this page is about. When the unexplained part is more than a third of the total movement, the card adds a note that says the split is rough: the price moved far enough to change the straddle’s sensitivity, or one side’s price is stale. The split is first-order, worked from the model’s sensitivities at the start of the day, not an exact accounting.

Strikes: IV at Each Strike

Which strikes cost more in IV, and how has the curve moved since the open?

Real tool · illustrative dataThe Strikes viewSwipe sideways to see all of itEnlarge

Close

The card is titled IV by strike. Each strike has its own IV, and they are not equal. Plotted against the strike they form a curve, called the smile or the skew; the at-the-money figure is only one point on it. The page solves one IV per strike, from that strike’s own Call and Put, and a strike whose price does not identify an IV is a gap in the curve, not a zero. Three choices keep the curve readable:

1. It opens zoomed. It draws 2.5 priced moves either side of spot, never fewer than 7 strikes. A day before a weekly expiry the far wings solve to very high figures on premiums of a few paise, and drawn whole they flatten the part anyone trades into a line along the floor. All strikes in Customise draws the whole solved ladder.
2. The priced range is shaded. It is spot plus and minus one priced move (the second answer), so the curve reads against the move the market is paying for. The key under the curve says Expected range ±378 pts, and beside it a count such as 38 of 52 strikes shown. (The pictures show the earlier words, Priced range from IV, spot ± 378 pts.) A line under the key says how many strikes were left out: no reliable IV.
3. The open curve is dashed beside today’s. Both are scaled together on round ticks.

The Pick-a-strike Readout and the Four Figures

Under the curve a readout follows the strike you pick (or the one nearest spot): IV now, Since open, Call price and Put price. Below the card, four figures sum the curve up.

Real tool · illustrative dataThe four figures below the curveSwipe sideways to see all of itEnlarge

Close

• ATM IV is the same figure as the first answer, with the open beside it.
• Range low and range high (each with its strike, for example 24150 · range low) are the listed strikes nearest the forward minus and plus one priced move (24150 and 24900 on the picture), each with its own solved IV, its IV at the open and the change. They are measured at a distance in priced moves, not a fixed per cent, because 5 per cent is deep in the wings a day before a weekly expiry and barely off the money a month out. One priced move away is the same place on every expiry.
• Dearer side is the lower strike’s IV minus the higher strike’s (Low minus high strike): 12.13% less 11.75% is +0.39 pts. Under 0.3 of a point the page says Both sides priced about the same. At 0.3 or more it says Strikes below spot cost more or Strikes above spot cost more. On an index the lower side usually costs more, because protection is bought and upside is sold. That is a statement about prices, not a forecast of a fall.

Real tool · illustrative dataHovering the curveSwipe sideways to see all of itEnlarge

Close

The same readout works on a touch screen and with a keyboard. The curve is one control (a slider with the label Explore implied volatility by strike): focus it with Tab, move with the Left, Right, Up and Down arrows, jump with Home and End, and press Escape to close the tooltip. The keyboard behaviour was read from the code and not run on every device (not tested).

Real tool · illustrative dataAll strikesSwipe sideways to see all of itEnlarge

Close

Real tool · illustrative dataThe open curve switched offSwipe sideways to see all of itEnlarge

Close

With the open curve switched off the view draws today’s curve alone (see Customise). If the latest snapshot carries no per-strike prices the card says No strike prices at this reading; if too few strikes show an IV it says Too few strikes carried a price that shows an IV to draw a curve.

Expiries: Every Live Expiry Side by Side

Which expiry is paying for the most movement each day, and what is the 30-day IV?

Real tool · illustrative dataThe Expiries viewSwipe sideways to see all of itEnlarge

Close

The card is titled Compare expiries. The view is a table, not a curve. The page reads at most 3 live expiries, and a few points drawn as a line would invite you to read a shape into them. Across, the rows answer the questions traders bring here:

The row of the expiry you are reading is marked. It is solved from the same archived reading as the insight above it, not from a separate chain fetch a minute apart, so the two never disagree. The other rows are read when the page opens and then at most once a minute (60 seconds), and only when a new reading has arrived. The line under the table says when: As of 11:30. If the other expiries cannot be read, the card says The expiries could not be read just now. with a Try again button.

Compare the Move per Day Down the Rows

The IV column is not comparable row to row. It counts calendar days, and a nearest expiry with one or two days left is a small number to spread a move over, so its IV reads high for that reason alone. The per-day move has no such clock in it. On the picture the three IVs are 11.84%, 12.82% and 13.29%, yet the three days are priced at ±198, ±203 and ±212 points: the farther expiries pay for a little more movement a day, and the move to expiry grows with the square root of time (378, 597, 889).

Real tool · illustrative dataThe same table on expiry day, 14:35Swipe sideways to see all of itEnlarge

Close

The Foot: a Blend Only When One Exists

The foot says Ranges are not predictions. Under it, How to compare expiries opens a short note: why a near expiry reads high in IV, why the move per day is the fair comparison, and the 30-day IV: “The blend gives a 30-day IV of 13.29%, used for IV Rank and IV Percentile”. Where the expiries do not reach far enough, it says These expiries do not reach far enough to blend a 30-day IV. Note that the sentence says “blend” also when none of the rows reaches 30 days and the furthest row simply stands in, as it does here (13.29% is the 27 Oct row’s own IV). An expiry that gave no reading is named in a line such as No reading for 13 Oct: option prices did not provide a usable IV.

Real tool · illustrative dataBANKNIFTY with one monthly expiry: the furthest stands inSwipe sideways to see all of itEnlarge

Close

History: the Past Year of 30-day IV

Is today’s IV high or low for the past year, and has it run above or below the moves the market actually made?

Real tool · illustrative dataThe History viewSwipe sideways to see all of itEnlarge

Close

This is the year-long view of IV: is today’s IV high or low for this underlying, and has it been running above or below what the market actually did? The card is titled 30-day IV history, or 30-day IV and HV when the HV line is on. It draws, on one right-hand axis, the 30-day IV close of each session (white, with its latest value tagged on the axis), and HV 20, the underlying’s historical volatility over the last 20 sessions (grey): the moves the market actually made. The year’s highest and lowest closes are ruled across as dashed lines, tagged 1-year high and 1-year low: they are exactly the two ends IV Rank divides by, so the rank in the opened insight can be read off the chart. The last point is today’s live 30-day IV, when it can be worked out and is later than the file’s last close. The card head says how far the closes run: Closes to the file’s last date (the picture shows the earlier words, Daily closes to 29 Sep 2026). On the live page the closes now run to 16 October 2026. The chart head counts the sessions drawn. The key reads 30-day IV, HV 20 and 1-year high / low, with India VIX and the close when they are on.

The row above the chart is as simple as on Intraday: plain text tabs for the window (1M, 3M, 6M, 1Y, with 1Y at first), a crosshair switch and full screen. There are no indicators, chart types, chart settings or drawing tools.

The Four Figures

The four figures are named in sentence case on the page: IV percentile (65, Above 65% of the last 252 closes), IV rank (29, Where today sits in the year’s range), the 1-year high (23.35%, On 1 Apr) and the 1-year low (9.18%, On 20 Nov). They are the figures of the fourth answer, with the dates of the two extremes. (With a history shorter than a year the two extreme cells still carry the labels 1-year high and 1-year low; read the sessions count in the chart head.)

Real tool · illustrative dataThe four figures under the year chartSwipe sideways to see all of itEnlarge

Close

Reading Two Lines Together

Hover the chart to read a day: the tooltip gives the date (with · live on the last point), the 30-day IV, HV 20, IV minus HV and any other line that is on.

Real tool · illustrative dataHovering a daySwipe sideways to see all of itEnlarge

Close

• IV above HV means the 30-day option prices ask for more movement than the last 20 sessions delivered. Option prices often carry a premium over the volatility that followed, so this is common; the picture shows the two lines crossing in both directions.
• IV below HV means the market has been moving more than option prices expected. It is worth noticing, not a signal.
• One window is not a verdict. HV 20 describes the past month; the 30-day IV describes the next. Neither says which way price goes.

India VIX and the Close

Real tool · illustrative dataIndia VIX and the NIFTY close switched onSwipe sideways to see all of itEnlarge

Close

India VIX is offered for NIFTY only, since it is NIFTY’s index; the switch does not appear for any other underlying (Customise). The close, on its own left axis, lets you see how the volatility moved against the price over the year.

When There Is No Year

The year of closes comes from one file. For an underlying that is not in it (a new listing, or a BSE index such as SENSEX or BANKEX, whose history is not collected yet) the card says so in a plain sentence in place of the chart, and the fourth answer says No year of IV closes for the symbol. A failed read says The year of IV closes could not be read just now (states).

D

Part D of 6 Customise and the states Every switch and its default, and what the page says when it has no number. 2 topics

The question each topic answers

1. What can I change in how the page reads, what are the defaults, and what is remembered?
2. What does the page say when it has no number, and what does each state mean?

Customise: Every Switch and Its Default

What can I change in how the page reads, what are the defaults, and what is remembered?

Real tool · illustrative dataCustomise on the Intraday viewEnlarge

Close

The Customise button in the page bar (a gear and the word) opens a panel under it. It is the same panel shell as the Option Chain’s. Every change applies at once, so the only buttons are Reset and a close button. Escape closes it and returns focus to the button. The panel holds one Contract section and one section for the view you are on: a view shows only the switches that change what it draws.

The Contract Row

The Expiry selector is the site’s one expiry control. It sets the expiry the insight, the Intraday view and the Strikes view read. On the History view the chart reads a 30-day blend of every expiry, so the expiry does not change it. On the Expiries view the page has nothing else to set, so the expiry selector stands in the page bar where Customise was.

Real tool · illustrative dataThe page bar on the Expiries viewSwipe sideways to see all of itEnlarge

Close

The Switches

The IV line itself is always drawn. Every other line is a switch, with the default shown in the table. Customise holds no chart settings, indicators or chart types: the charts have none. The symbol in the labels follows the underlying you are reading (for BANKNIFTY the labels say BANKNIFTY).

Real tool · illustrative dataCustomise on the Strikes viewEnlarge

Close

Real tool · illustrative dataCustomise on the History view (NIFTY)Enlarge

Close

Real tool · illustrative dataThe same panel for BANKNIFTYEnlarge

Close

What Is Remembered

• The switches are kept in this browser, field by field (key ivCustomise:v1), so a stale or hand-edited entry cannot break the page. Reset returns them to the defaults above.
• The view you left is remembered the same way (ivView:v1), so the page reopens on it.
• The expiry is not a preference. It is the contract being read, so Reset leaves it alone and the page does not store it.
• No chart window or rewind is ever stored. Reopening tomorrow on yesterday’s instant would chart a stale moment with nothing to say it was not current.

Nothing is sent to a server. In a private window or with site data blocked, a change lasts for the visit only.

Every State the Page Can Be In

What does the page say when it has no number, and what does each state mean?

The page keeps four things apart that are easy to confuse: still reading, nothing to show, could not read and the first reading of a new session. While data is still being read the page says so, and a figure that could not be measured is named, never drawn as zero.

Real tool · illustrative dataThe first reading of a sessionSwipe sideways to see all of itEnlarge

Close

This is what the page shows when the day’s minute archive is empty: the app seeds one reading from the current chain. (While the archive is still being read, the page shows Reading today’s option prices instead.) The verdict pill reads First reading, and each change says why it is empty, for example “This is the session's first reading, so the 5-minute window has no baseline yet.” The answers still work, because they need the chain, the daily closes and the year, and not the archive. The chart needs two readings to draw a line.

Real tool · illustrative dataThe year file cannot be readSwipe sideways to see all of itEnlarge

Close

Real tool · illustrative dataThe unavailable stateSwipe sideways to see all of itEnlarge

Close

The fourth answer and the verdict also change when the year is missing: see the verdict words. And on a settled expiry no reading is possible at all: the page says This expiry has settled and quotes This series has settled, so its option prices no longer describe a live contract.

E

Part E of 6 Why it moves, and why it disagrees Calendar days, the forward, the Call and Put check, and why another platform shows another figure. 3 topics

The question each topic answers

1. Why does IV jump on a Monday and race up on expiry day when nothing has happened?
2. Why is the centre the forward and not spot, and why should a Call and a Put show the same IV?
3. Why does another platform show a different IV for the same option, and is either wrong?

Calendar Days: Mondays, Holidays and Expiry Day

Why does IV jump on a Monday and race up on expiry day when nothing has happened?

The page’s IV is the volatility that, spread over the calendar days to expiry (to the 15:40 close), gives the option’s price. What the market really charges is a move over the sessions left. Put the two together and the same per-session price gives a different IV on different days:

Monday After a Holiday Weekend

The next picture is the real page on an illustrative Monday, 5 October at 14:20. Friday 2 October (Mahatma Gandhi Jayanti) is a holiday in the app’s own calendar, so the previous session was Thursday 1 October and three days (Friday, Saturday, Sunday) were shut.

Real tool · illustrative dataMonday 5 October, 14:20, after a holiday weekendSwipe sideways to see all of itEnlarge

Close

The insight row says ATM IV is up +6.96 pts against Thursday’s close, from 9.71% to 16.67%. The Today section says the day being priced is about the same: from ±197 pts at the previous close to ±199 pts. Nothing happened. The factor of 0.76 at Thursday’s close and 1.29 on Monday afternoon explains it: 9.71 ÷ 0.76 is about 12.76 and 16.67 ÷ 1.29 about 12.95 on a session clock, within 0.2 of a point of each other (worked from the unrounded factors). This is why the page leads with points per session, and why the opened insight always carries the note about calendar days.

Real tool · illustrative dataThe Intraday chart the same afternoonSwipe sideways to see all of itEnlarge

Close

The same effect makes IV dip into every weekend and recover after it, which is why a long weekend shows a sag in the IV line. It is a convention of the calculation, not a change in the market.

Expiry Day

Real tool · illustrative dataTuesday 6 October, 14:35: expiry daySwipe sideways to see all of itEnlarge

Close

With 65 minutes left to the close, IV reads 29.35%. That looks extreme and means very little: about one ten-thousandth of a year is left, so every rupee of premium is a large figure when written as a yearly percentage. The useful figures are in points: the move left today is ±80 pts, and the page says the options are priced for days 0.52× the size of recent ones, because a remaining part of a day is set against a whole actual day of ±154. Read it as arithmetic: late on expiry day the number is still computable, but one tick can move it by a large fraction of a point, so it should not be read as though it were precise. The page adds no separate warning for this; it says the move is all of today’s and nothing more.

After the close on expiry day the expiring series has settled, so the page leaves it and moves to the next expiry. On Monday 19 October 2026, for example, once the market had closed, the page showed the 27 October expiry (expiry dates not checked against an exchange circular). The 30-day IV and the year are not affected: the year never reads an expiry on the day it settles (how the year is built).

The Forward, Not Spot; and the Call and Put Check

Why is the centre the forward and not spot, and why should a Call and a Put show the same IV?

The Centre Is the Forward

“At the money” sounds as if it means “at the current price”. For option pricing it does not. The centre of the distribution an option is priced against is the forward, which sits above spot by the cost of carrying a position to expiry. On the first picture the detail panel read the IV at 24539 while spot was 24512.35, about 27 points higher, and the straddle used the 24550 strike, the one nearest the forward, where the strike nearest spot is 24500. Reading “ATM IV” at the strike nearest spot reads the smile at a point systematically off its centre, and picks up a slice of the curve’s slope with it. The gap grows with time to expiry: at 6.5% a year and 30 days it is more than two strikes on NIFTY.

The page recovers the forward from the option prices themselves, with the Call and Put prices of the strikes nearest spot, so it needs no futures quote. The Option Chain page works differently: it prefers the forward implied by the vendor’s own IV and falls back to this method, so its IV column and this page’s ATM IV can differ slightly for that reason.

Why It Is Interpolated

The forward almost never lands on a listed strike. If the page read the nearest strike, the figure would step each time the forward crossed the midpoint between two strikes, by the slope of the smile over one strike interval. In a chart updated every minute that step looks like a real move, and it recurs all session. So the reading is interpolated between the strikes either side of the forward, in total variance, which makes it continuous.

One IV per Strike, From the Straddle

Put–call parity is not a model. It says a Call minus a Put at one strike equals the discounted gap between the forward and the strike, so if the centre is right one volatility reprices both legs. The page therefore solves one IV per strike by inverting the Call plus Put together. The straddle’s price barely depends on the forward at the money, so it is first-order immune to the very error that would split the two legs apart. Averaging two separately solved IVs is a different operation and a worse one: away from the money, an error in the centre turns a flat surface into a false skew that looks entirely plausible.

The Call and Put Gap Is a Data Check

The tooltip’s line Call vs Put and the detail panel’s sentence “at 24550 the Call alone solves 0.00 pts from the Put alone” report the difference between the IV of the Call alone and the Put alone at the strike nearest the forward. Near zero means the centre is right. A larger gap is a measurement of how far off the centre is, to first order, or of a stale quote. Some readers treat it as a directional signal. It is not one. There is a second cause as well: at any strike one leg is in the money and mostly intrinsic value, trades in a wider spread and barely moves with volatility, so inverting its price is numerically unstable and a stale quote on it can make a large and fictional gap. The page lists the gap as a check and never as a signal.

Why Two Platforms Show Different Numbers

Why does another platform show a different IV for the same option, and is either wrong?

The same option, at the same moment, will show different implied volatilities on different services, and none of them is necessarily wrong. IV is not observed. It is solved for, and the answer depends on the inputs chosen. This is what this page fixes:

Last traded price can be minutes old on a thin strike; that is the price of a rule that never uses a quote nobody has traded at. The practical consequence: comparing an IV across platforms means little unless both state their method, whereas comparing a figure against itself over time, from one consistent method, means a good deal. That is the comparison this page is built for.

India VIX Is a Different Figure

For NIFTY the detail panel prints India VIX among its calculations, and the History view can draw it. NSE builds the index from NIFTY’s near and next month options across every strike to a steady 30 days. Because out-of-the-money Puts carry more IV than the at-the-money strike, it usually reads a little above an at-the-money 30-day IV (the page’s own note says about a point). On the picture VIX is 13.41 and the 30-day IV 13.29%, only 0.12 apart: the invented market does not follow the page’s remark about a point. Treat it as a yardstick for whether the page’s NIFTY reading is in the right place, not as the same number. We have not checked the index method against NSE’s own document (What we have not verified).

F

Part F of 6 Using it Routines for an ordinary day and expiry day, three worked readings, the traps, and the phone. 5 topics

The question each topic answers

1. In what order do I read the page on an ordinary day, on expiry day and over a week?
2. What does a full reading look like on real screens of the page, and what would I not conclude from it?
3. What do readers get wrong about IV, and what should I check before I act on a reading?
4. Which page do I open for which question about volatility and price?
5. How do I read the page, and this guide, on a phone?

Routines: an Ordinary Day, Expiry Day and a Weekly Check

In what order do I read the page on an ordinary day, on expiry day and over a week?

A routine is an order of questions, so that the same reading is made the same way each time and a change in the answer means a change in the market, not in your habit. These three use only what the page prints.

An Ordinary Day (about three minutes)

1. Check the time in the insight row. If it is not today’s, every figure is as of that time.
2. The move in points (the first sentence of the opened insight), then the priced day against the actual day (the third sentence).
3. The year (the second sentence and the verdict word): IV Percentile, IV Rank in the detail panel, and whether the window is a full year.
4. The change since yesterday in points per session (the Today section of the detail panel), not in IV points after a weekend or holiday.
5. One view to answer the next question: Strikes for which side costs more, Expiries for which expiry pays most per day, Intraday for how the day has moved.

Expiry Day

1. Ignore the large IV figure and read the move left today in points (the detail panel calls it Priced move left today).
2. Read the straddle price in the Expiries view; it shrinks through the afternoon, and the straddle split on Intraday says how much of that is time.
3. Look at the Strikes view with the open curve on: expiry-day curves can be steep, and the gap between the two curves is the day’s repricing.
4. Remember the limit. In the last hours one tick can move the solved IV by a large fraction of a point. The figure is computable and no longer precise.

A Weekly Check for a Position You Hold

1. Open the Expiries view and compare the per-day column down the rows, not the IV column.
2. Open History: where is the 30-day IV in its year, and above or below HV 20?
3. Note the IV Percentile and the move per day, and compare them with last week’s note. The page stores no history of your readings; a note on paper does it.
4. Write down what the numbers say and what they do not. They never say which way the price goes.

Before a known event (results, a policy decision), the Expiries view marks, for a stock, the first expiry on or after the results date. IV tends to be bid up ahead of a scheduled event and to fall once it has passed, whichever way the price went; an option held through such an event can lose value even when the direction was right. That is a general feature of option pricing, not a measurement the page makes.

Three Worked Readings

What does a full reading look like on real screens of the page, and what would I not conclude from it?

Each example reads the page in the routine’s order and ends with what the reading does not say. The market is illustrative. The figures are the ones the pictures print.

Mistakes and Traps

What do readers get wrong about IV, and what should I check before I act on a reading?

• Calling a level high or low on its own. “IV is 16” means nothing without a comparison: recent days, its own year, or today’s range.
• Reading IV as direction. A rising IV is not bullish or bearish. It can rise in a falling market and in a rising one, because both are movement.
• Comparing IV across days after a break. A Monday’s IV against a Friday’s is a calendar comparison. Use points per session.
• Comparing the IV column down the Expiries rows. Compare the per-day column.
• Treating 1 SD as a limit. About one outcome in three lands outside it, and the distribution is not symmetric.
• Trusting a rank built on a short history. IV Rank needs 252 sessions and rests on two days. A single spike can hold it low for a year. IV Percentile uses every day.
• Reading the Call against Put gap as a signal. It is a data check on the centre.
• Treating 29% on expiry day as stress. It is largely the clock. Read the move left, in points.
• Comparing one platform’s IV with another’s. Rates, centres and prices differ (why).
• Expecting the year to be NSE data. The pictures’ year is invented; on the live page it is NSE’s closing prices through the file’s last date, followed by today’s own reading.
• Forgetting events. IV tends to be bid up ahead of a scheduled event and to fall after it. A correct view of direction can still lose value in the option.
• Acting on a stale reading. Look at the time of the data in the insight row first.

This guide describes a tool. It is education, not advice. The risk disclosure in the footer of Sahi guide pages says that 9 out of 10 individual traders in equity Futures and Options incurred net losses. Selling options can lose more than the money put up, and nothing on this page limits that.

Which Tool When

Which page do I open for which question about volatility and price?

The guides for each tool are linked in Read next at the foot of this page.

Reading It on a Phone

How do I read the page, and this guide, on a phone?

At 768 pixels and below the page has a phone layout of its own. In short: the insight row sits on top, and the Intraday and History charts fill the rest of the screen. What changes:

• The views stay a capsule across the top (or fold into a menu that shows the name of the view when the bar is too narrow).
• The insight row is a closed row with the symbol and the verdict (in sentence case, for example Normal IV). It opens as a sheet over the page, and the four answers are in the sheet.
• Intraday and History fill the screen. The chart takes all the room under the insight row. The key moves to its own line under the card title. The four History figures and the straddle split follow below; scroll down for them.
• Tabs and tools share one row. The interval tabs (1m to 1D on Intraday, 1M to 1Y on History) sit on the left, and the crosshair and full screen on the right. The head above shows only the figure and its change; the time and spot are in the tooltip when you touch the chart.
• The Intraday card keeps its scope line under the plot (6 Oct expiry · 30 Sep session), which a desktop leaves out.
• Customise opens from the settings button in the top bar as a sheet from the bottom; the button in the page bar is hidden at this width.
• Strikes and Expiries scroll as before. The percentage scale of the smile sits in a gutter at the right.

Real tool · illustrative dataOn a phone: the top of the pageEnlarge

Close

Real tool · illustrative dataScrolling down to the chartEnlarge

Close

Real tool · illustrative dataThe insight opened as a sheetEnlarge

Close

Real tool · illustrative dataCustomise as a bottom sheetEnlarge

Close

Reading this guide on a phone. A wide picture scrolls sideways inside its frame, with a line that says so and an Enlarge button that opens it full size. Tables scroll sideways too. Rotating the phone gives the pictures more room. The phone pictures were taken at 390 pixels, one common phone width; other widths were not captured. The chart tools and the sheet behaviour were read from the code and the pictures, not tried on a physical phone (not tested).

What the Page Does Not Do

What does the page not do, and where does a reading stop being worth much?

• It does not forecast. It never says which way price will go, how much it will move, or whether options are a good buy. The priced move is what the prices pay for. The sentence about recent days compares with the past.
• It reads one underlying and one expiry at a time in its insight, Intraday and Strikes. The Expiries view reads up to 3 expiries; History reads a 30-day blend of all of them.
• It depends on the day’s archive. Without it, the page shows one reading and says so. A minute with no snapshot is a minute with no reading.
• It does not solve every strike. A strike whose price barely moves with volatility (deep in the money, or a few paise) is left out, not guessed.
• It is least precise in the last hours before expiry, when one tick can move the solved IV by a large fraction of a point. It adds no separate warning.
• A settled expiry gets no reading. The page refuses rather than show a number that looks like a good one.
• The year has limits. It is a file of daily closes that ends at its last date (16 October 2026 at the time of writing), followed only by today’s own reading; SENSEX and BANKEX are not in it; a new listing has a short history, named as such.
• It does not compute margin, costs or a position’s profit and loss. It does not place orders.
• It keeps no history of your readings. Only the Customise switches and the last view are stored, in this browser.
• It is a pricing-model reading. Black–Scholes in forward form at a fixed 6.5% rate. Another model, rate or price gives another IV, which is why platforms differ.

What We Have Not Verified

Which statements in this guide could we not confirm, and what should I check myself?

Everything in this guide about how the page behaves was read from the page’s own program code or taken from a picture of the page. The items below are the ones we could not confirm. Where the guide touches one of them it links here instead of stating it as fact. For the exchange rules we tried the exchanges’ own pages and could not open them, so we have left the rules out rather than repeat them from memory.

If you find any of these settled by an official source, the guide can be updated: each one has a place in Sources.

Glossary

What does each word mean?

Underlying

The index or share an option is written on, for example NIFTY. Its price is called spot.

Premium

The price of one option, in rupees per unit. The chain prints it as the last traded price. It is the number from which implied volatility is worked out.

Call, Put

A Call gives its holder the right to buy the underlying at the strike; a Put gives the right to sell it. A Call gains when the price rises above the strike, a Put when it falls below. (Some screens and the exchange use the codes CE and PE for the same two.)

Strike

The price at which the holder of a Call may buy, or the holder of a Put may sell, the underlying.

Expiry

The date on which an option ends. The page counts time to the close of the option market on that date (15:40 from 3 August 2026).

At the money (ATM)

An option whose strike is at, or nearest to, where the underlying stands. On this page the centre is the forward, not spot.

Time value

The part of an option’s premium above what it would be worth if it ended now. It is what is paid for the movement that may happen before expiry, and it is the part implied volatility prices.

Implied volatility (IV)

The size of move an option’s price is paying for, written as a yearly percentage. It is worked out from the price, not forecast. Higher IV means dearer options. It says how big a move is priced, never which way.

Vol point, IV point

One percentage point of implied volatility: 12.00% to 13.00% is one vol point. A change in IV is written in points ("−1.00 pts").

ATM IV

The implied volatility at the forward, taken from the Call plus Put (the straddle) at the two strikes either side of it and interpolated between them, so it does not jump when the price crosses a strike.

Forward

Where the option prices put the underlying at expiry: spot plus the cost of carrying it until then. The page reads it from the traded Call and Put prices, using put–call parity, at a fixed yearly rate of 6.5%.

Put–call parity

A relationship that holds whatever the model: a Call minus a Put at one strike equals the discounted gap between the forward and the strike. It means one volatility reprices both legs of a strike.

Straddle

The Call and the Put of one strike taken together. Its price is the Call premium plus the Put premium.

Standard deviation (1 SD)

A yardstick for the size of a move. The priced move to expiry is one standard deviation: the pricing model puts about two outcomes in three inside it. It says nothing about which side.

Priced move

The move the at-the-money IV pays for, in points: spot × IV × √(days left ÷ 365). One standard deviation. Printed to expiry and per day.

Session

One trading day. Weekends and exchange holidays are not sessions: the market is shut and the page counts no movement on them.

Priced move per day

The priced move to expiry divided by the square root of the sessions left: what one session is priced for. On the last session it is the whole move left today.

Historical volatility (HV 20), actual day

How big the underlying’s days have actually been: the standard deviation of the last 20 close-to-close moves, scaled to a year. The page converts it to points for one day and calls it the actual day.

Priced against actual

The priced day divided by the actual day, from the whole points the page prints. At 1.2 or more the page says bigger; at one over that or less, smaller; between, about the same.

IV Percentile (IVP)

The share of the last 252 closes of the 30-day IV that closed below today’s. Shown once 60 sessions of closes exist.

IV Rank

Where today’s 30-day IV sits between the year’s lowest and highest close, from 0 to 100. It waits for a full 252 sessions, and rests on two days only.

30-day IV

A steady reading blended from the expiries around 30 days, so the year is not ranked on the weekly sawtooth of the front expiry.

Calendar days

IV counts every day to expiry, weekends and holidays included, as brokers and India VIX do. The market only moves on sessions. That is why the IV of a front expiry dips into a weekend and jumps after it.

Smile, skew

Options at different strikes of one expiry carry different IVs. Drawn against the strike, the pattern is the smile. On an index the strikes below spot usually cost more.

India VIX

NSE’s 30-day volatility index on NIFTY. The page shows it beside NIFTY’s own figures as a yardstick. It is a different method from the page’s ATM IV, so the two are not the same number.

Vega

The rupees an option’s premium moves for one vol point. An option with almost no vega cannot show an IV: its price hardly moves with volatility, so the page does not solve it.

Time decay (Theta)

The premium an option loses as time passes with nothing else changing.

Open Interest

The number of option contracts open at a strike. This page does not use it: the IV is worked out from traded premiums.

Last traded price (LTP)

The price of the latest trade in a contract. The page solves IV from the last traded price of each leg, not from the bid–ask midpoint. On a thin strike it can be minutes old.

Questions Readers Ask

What do readers ask most?

Sources

Where does each statement in this guide come from?

The guide rests on the program code of the Implied Volatility page and on pictures of the page itself. The constants below are quoted in the text from one list (scripts/guides/implied-volatility-parts/limits.mjs); each row names the file the value comes from. No official exchange or regulator document is cited as proof of an exchange rule: the rules we could not confirm are in What we have not verified.

Where Each Part Comes From

The Numbers the Guide Quotes

Exchange Facts Looked For

We searched for the exchanges’ and regulator’s own statements on the close of the derivatives market from 3 August 2026, the settlement price on expiry day, and the construction of India VIX. The exchanges’ own pages did not open from our tools, so none of these is cited here as verified.

The Pictures

Each picture is a capture of the real page on an invented market, taken with the page clock frozen at the moment named in the caption. They are regenerated with node scripts/guides/shot-implied-volatility.cjs, and the figures in the text are checked against figures.json, which that script writes, every time the guide is built.