Volatility
IV Percentile
Also called: IVP, implied volatility percentile
IV percentile is the percentage of trading days over a lookback window (usually one year) on which implied volatility closed below its current level. An IV percentile of 80 means IV has been lower than today 80% of the time.
Where IV rank compares today's IV with the extremes of the range, IV percentile compares it with the full distribution of daily readings. That makes it robust to one-off spikes: a single crash day raises the yearly high and compresses IV rank, but it adds only one day to the percentile count.
Read together, the two metrics describe the shape of the year. A high percentile with a low rank means IV is elevated relative to most days but far below a past spike; a high rank with a high percentile means IV is genuinely near the top of its recent history.
Formula
IV Percentile = (days in lookback with IV below IV_now) / (days in lookback) × 100
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Frequently asked questions
Which is better, IV rank or IV percentile?
Percentile is more stable after volatility shocks; rank is more intuitive about distance from the extremes. Most tools show both, and they agree in ordinary conditions.
What lookback does IV percentile use?
The convention is 252 trading days, one year. Shorter windows react faster to regime changes but lose context; ImpliedOptions reports the window alongside the value.