All termsOption Pricing and ValueStart here
IV Percentile
IV Percentile measures the proportion of observations in a chosen historical period during which implied volatility was below the current level.
Why it matters to you
IV Percentile answers a different question from IV Rank. IV Rank asks roughly: Where is current IV within its historical high low range? IV Percentile asks: How often has IV been lower than it is now? The two metrics should not be treated as interchangeable.