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What is IV rank?

In one line: IV rank shows where today's implied volatility sits between its lowest and highest level of the past year, on a scale from 0 to 100.

Trading glossary · Updated 2026-10-21

A simple example

Implied volatility (IV) is how big a move option prices are expecting. A raw IV number like 30% is hard to judge alone. Is that high for this stock or low?

IV rank answers that. The formula:

1. Find the lowest IV of the past 52 weeks. Say 20%.
2. Find the highest. Say 60%.
3. Take today's IV. Say 30%.
4. IV rank = (30 − 20) ÷ (60 − 20) × 100 = 25.

So today's IV is a quarter of the way up its one-year range. Fairly low for this stock.

If today's IV were 55%, the rank would be (55 − 20) ÷ 40 × 100 = 87.5. Near the top.

Why it matters

Each stock has its own normal. 30% IV is quiet for one stock and wild for another. IV rank puts them all on the same 0–100 scale.

High IV rank means options are priced for bigger moves than usual. Low IV rank means they're priced for calm. That helps you see whether an option is "expensive" or "cheap" compared with its own past.

A common mistake

Mixing up IV rank and IV percentile. IV percentile counts how many days in the past year IV was lower than today. They can give very different answers.

One spike can wreck IV rank. Say IV hit 150% once during a crash. Now almost every normal day looks like a low rank, even if IV is fairly high. Check whether one wild day is stretching the range.

Questions