IV Rank vs IV Percentile: What They Mean, With a Worked Example

IV Rank vs IV Percentile

Both put today's implied volatility in context, but they answer different questions. Rank asks where today sits between the year's high and low. Percentile asks how many days were lower.

Worked example (EXMPL)

EXMPL implied volatility ranged from 20% to 80% this year, but it only hit 80% for a few days around a surprise announcement. Today it is 32%.

IV rank = (32 − 20) ÷ (80 − 20) = 20. That looks low.
IV was below 32% on 180 of 252 days, so IV percentile = 71. That says today is higher than usual.
When the two disagree, a one-off spike is usually the reason.