--- title: "IV Rank and Percentile Calculator, Nifty and VIX | RupeeCase" description: "Free IV rank and IV percentile calculator on dated NSE series: Nifty 30 day at the money IV and India VIX, with both definitions worked out." source_url: "https://www.rupeecase.com/learn/tools/iv-rank-percentile" --- * IV rank**19%**where the reading sits between the low and the high * IV percentile**63%**share of days with a lower IV * Nifty 30 day at the money IV**12.44**15 Sep 2026 * Window**252 sessions**9 Sep 2025 to 15 Sep 2026 ### IV rank How far the reading sits between the lowest and the highest in the window. (12.44 − 8.62) / (29.22 − 8.62) = **19%** Low 8.62 on 24 Dec 2025, high 29.22 on 30 Mar 2026. One spike sets the high and keeps the rank low for months. ### IV percentile The share of days in the window on which the level was lower than the reading. 159 of 252 days below 12.44 = **63%** It counts days, so one spike does not stretch it. Some platforms count days at or below; the difference is a point or less over this window. Percentile reads 45 points above rank: a spike earlier in the window stretches the range, so most days were below the reading while the rank stays low. IV rank is 19% and percentile is 63% for the same reading Nifty 30 day at the money IV for the 252 sessions to 15 Sep 2026. The lines mark the lowest and highest readings; the dot is the reading used. Source: NSE end of day data, computed by RupeeCase. As of 15 Sep 2026.The same reading, placed two ways Rank uses the lowest and highest readings only. Percentile uses every day in the window. Source: NSE end of day data, computed by RupeeCase. As of 15 Sep 2026. The Nifty series is computed by RupeeCase from NSE settlement prices: the at the money implied volatility of the two nearest monthly expiries, blended to a constant 30 days. It reads a little under India VIX, which uses the whole smile. Series from NSE end of day files, ending at least 30 days before the page date. Not live, not a signal, and this page cannot trade. ## How to read it ### IV rank Where the reading sits between the lowest and the highest in the window: the reading minus the low, divided by the high minus the low. One spike sets the high and keeps the rank low for months. ### IV percentile The share of days in the window with a lower reading than the one picked. It counts days, so one spike does not stretch it. ### Why they differ After a spike, rank stays low while percentile is high: most days were below the reading, but the range is wide. The buttons jump to the date where the two are furthest apart in the window you picked. ### Windows and series The window is in sessions, not calendar days: 252 is about a year. The Nifty series is computed by RupeeCase from NSE settlement prices; India VIX is the value NSE publishes. Both definitions are taught in [the IV rank and percentile module](/learn/path-16/module-16-4-iv-rank-and-iv-percentile). ## What it leaves out A window is a choice and the answer moves with it. A high rank says implied volatility is high against its own recent range, not that options are expensive: realised volatility is the other half of that comparison. The file holds 300 sessions from 1 Jul 2025, so a 252 session window exists only for the last 49 dates, and a shorter window opens up earlier dates. ## Go to the source 1. [NSE, India VIX: what it measures and how it is computed](https://www.nseindia.com/static/products-services/indices-indiavix-index) What does an IV percentile of 80 mean?Implied volatility was lower than today on 80% of the days in the window. It does not mean options are 80% overpriced, or that IV is 80% of its high. Do all platforms use the same definitions?No, and some swap the two names. Read the definition on the page before comparing numbers across tools. Is this live?No. The series end on the date shown, at least 30 days before the page date, and the page never shows live data. 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