IV Rank & Percentile

advanced6 min read

Is volatility high or low right now? Context that decides whether you buy or sell premium.

Knowing the implied volatility number isn’t enough — “IV is 30%” means nothing without context. Is 30% high or low for this stock? IV Rank and IV Percentile answer exactly that, by comparing today’s IV to its own history (usually the past year).

IV in isolation is meaningless; IV relative to its own range is everything — because that context tells you whether to be a buyer or a seller of options. The strategy is simple and powerful: when IV is high relative to history (IV Rank near 100), options are expensive, so you lean toward selling premium (and IV tends to mean-revert down, helping you). When IV is low (IV Rank near 0), options are cheap, so you lean toward buying premium (IV tends to revert up, helping you). IV Rank/Percentile turns the abstract IV number into a clear buy-or-sell compass. You’re trading the *mean-reversion of volatility itself*, which (recall the volatility module) is one of the most reliable behaviours in markets.

IV Rank — where current IV sits between its 1-year low and high (0 = at the lowest, 100 = at the highest).
IV Percentile — the % of days over the past year that IV was below today’s level (a similar, often more robust gauge).
The rule of thumb — high IV Rank → favour selling premium (expensive, likely to fall); low IV Rank → favour buying premium (cheap, likely to rise).

ExampleA stock’s IV is 40%. Sounds high — but if its IV ranged 35–80% over the past year, an IV Rank of ~14 means it’s actually near the low end: options are relatively cheap, favouring buyers. Another stock at IV 25% with a yearly range of 10–28% has an IV Rank of ~83 — expensive relative to itself, favouring sellers. The raw numbers lied; the rank told the truth.

Key takeawayIV Rank/Percentile place today’s IV against its own past-year range, turning a meaningless absolute number into a buy-or-sell compass: high IV Rank → options expensive → favour selling; low IV Rank → cheap → favour buying. You’re trading volatility’s mean-reversion.

FAQs

IV Rank or IV Percentile — which should I use?

Both answer “is volatility high or low for this name?” IV Rank is simpler (position within the high-low range) but can be skewed by one extreme spike; IV Percentile (share of days below current IV) is often more robust to outliers. Either works as a compass — the key is using *relative* IV context, not the raw number.