IV rank and IV percentile
The short answerIV rank places today’s implied volatility on a scale from the lowest (0) to the highest (100) of the past year. IV percentile is the share of the past year’s days on which implied volatility was lower than today. They answer the same question — are options cheap or expensive for this ticker? — with different math, and can disagree a lot.
The two formulas
IV rank = (IV today − lowest IV of the year) ÷ (highest − lowest) × 100.
IV percentile = the number of days in the past year with IV below today ÷ the number of days × 100.
Why they disagree
One violent spike stretches the year’s high. After it, today’s IV looks low on IV rank (it is far below that one high day) even if it is higher than on most days — which IV percentile shows. When the two disagree, percentile usually describes the year better; rank tells you how far you are from the extremes.
How traders use them
- High rank / percentile: options are expensive against the ticker’s own past. Option sellers like this environment; buyers pay up.
- Low rank / percentile: options are cheap against the past; buying options costs less, selling earns less.
- Compare with realised volatility — how much the price has actually moved. Implied far above realised means the market is paying for uncertainty (often before earnings).
Both measures compare a ticker only with itself: an IV rank of 80 on a quiet utility can still be a lower IV than a rank of 10 on a meme stock.
Live example: SPY and QQQ today
From the close of Fri, Nov 13, 2026 — this box is rebuilt after every trading day.
SPY on Nov 13, 2026: 30-day implied volatility 15.0%, IV rank 27, IV percentile 65; the price actually moved at 22.2% a year over the last 20 sessions.
The two disagree by 38 points — the past year had a spike that stretched the high, so rank looks lower than most days suggest. This is exactly the case described above.
QQQ: IV 25.2%, IV rank 55, IV percentile 85.
IV rank for every ticker: the Scanner · each ticker page.
Questions and answers
What is a good IV rank to sell options?
Many option sellers look for IV rank above about 50, when options are expensive against the past year — but a high rank before earnings is usually there for a reason.
Is IV percentile better than IV rank?
Percentile is less distorted by a single spike, so it often describes the year better. Rank shows the distance from the extremes. Looking at both is best.
How long a history do they use?
Usually one year (about 252 trading days), as on this site.
All 10 lessons: Learn · every term in one long page: the full guide · the numbers for any ticker: ETFs, stocks. For education only — not investment advice.