What is IV rank?
What is IV rank actually for?
IV rank places current implied volatility inside its own historical range. A high rank means current IV sits towards the top of the comparison window, a low rank towards the bottom. The rank does not replace a look at the underlying, the expiration, or the absolute price of the option.
How IV rank is calculated
IV rank places current implied volatility inside the range it covered over a reference window, usually one year: current IV minus the low, divided by the distance between high and low, times one hundred. Zero is the yearly low, one hundred the yearly high. It is not IV percentile, which instead counts on how many days IV closed lower.
Both metrics assume there is enough history to look at. On a recently listed underlying, or on thinly traded options, the reference window is incomplete — and the rank then describes the state of the data rather than the state of the market.
What the readings mean in practice
A high IV rank means options are expensively priced against their own history — the same strike distance pays more premium. A low rank makes buying relatively cheaper. Because the formula only knows two extremes, one outlier distorts the rank for months: a rank of 30 after a volatility shock is a different situation from a rank of 30 in a quiet year.
The reference window is part of the number. A rank computed over 252 trading days describes something different from one computed over three months, and vendors do not all calculate it the same way. Comparing ranks across two platforms often means comparing two different metrics that share a name.
The common misreading
IV rank is a comparison, not a trading rule. It says nothing about whether IV keeps rising, whether the underlying is liquid enough, or whether the expiration fits your thesis. A high rank and a bad fill add up to no edge at all. And a rank of 90 may simply mean the market is right to expect a large move.
Strategies where the term matters
- Bull Put Spread — Do you want a credit against an obligation - or would you rather pay a debit?
- Short Iron Condor — Is the range you expect genuinely narrower than the move the market has priced in?
- Long Straddle — Does the move have to be bigger than the one the market has already priced in?
Related terms
Every term in one place: the options glossary.
This material is general information about option strategies, written for a general audience. It is not investment advice, not a recommendation, and not financial analysis. Options can lose their entire value, and uncovered positions can lose more than the amount committed. Anything said about tax is general in nature and is no substitute for professional tax advice. Last reviewed: 2026-08-06.