Percentile to Stanine Calculator
Convert a percentile rank into its stanine (1–9) score using the standard normal-curve boundaries.
How it works
Stanine 1: <4th pct · 2: 4–10 · 3: 11–22 · 4: 23–39 · 5: 40–59 · 6: 60–76 · 7: 77–88 · 8: 89–95 · 9: ≥96
A stanine ("standard nine") compresses a percentile rank onto a 1–9 scale with a mean of 5 and a standard deviation of about 2. The boundaries are fixed by the normal curve: the middle stanine (5) covers the central 20% of scores, and the extreme stanines (1 and 9) each cover roughly the outer 4%. Because a single stanine spans a range of percentiles, small percentile differences near a boundary can shift the stanine while large gaps in the middle may not.
Worked example
A student at the 63rd percentile is above the 60th-percentile boundary but below the 77th, so they land in stanine 6 — the top of the "average" band.
Sources: Stanine — Wikipedia
Frequently asked questions
What is a good stanine score?
Stanines 1–3 are below average, 4–6 are average, and 7–9 are above average. A 5 is exactly average. Because the scale is coarse, treat a difference of one stanine as small unless it crosses a band.
Why use stanines instead of percentiles?
Stanines smooth out the false precision of percentiles. Reporting a child scored "in stanine 6" avoids implying that a 63rd and a 66th percentile are meaningfully different when they are not.
How do stanines relate to the normal curve?
They are equal-width bands of the standard normal distribution measured in half–standard-deviation steps around the mean, which is why the middle stanines are wide in percentile terms and the edges are narrow.
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This calculator is for educational purposes. Double-check important results before acting on them.