Stanine stands for "standard nine." It is a method of scaling scores on a nine-point scale where 5 is the mean and each unit represents half a standard deviation. Stanines 1–3 are below average, 4–6 are average, and 7–9 are above average.

What percentile is stanine 5?

Stanine 5 covers the 40th to 59th percentile — the middle 20% of the distribution, which is the average range.

How is a stanine calculated from a percentile?

Standard cutpoints divide the normal distribution into nine unequal segments. Percentiles below 4 → stanine 1; 4–10 → 2; 11–22 → 3; 23–39 → 4; 40–59 → 5; 60–76 → 6; 77–88 → 7; 89–95 → 8; 96 and above → 9.

Can I convert a z-score directly to a stanine?

Yes. The formula is stanine = round(2 × z + 5), clamped to the range 1–9. For example, a z-score of 0 gives stanine 5, and a z-score of +1.5 gives stanine 8.

Are stanines still used today?

Yes, stanines appear in many standardized educational tests (e.g., Iowa Assessments, Cognitive Abilities Test) and some psychological assessments. They are valued for grouping scores into broad, meaningful bands that reduce false precision.

Stanine Converter

Convert a percentile rank or z-score to a stanine (1–9) and see the corresponding performance band.

Convert to Stanine

Percentile Rank (0 – 99)

Enter a value and click Convert

Stanine Reference Table

Stanine	Percentile range	% of population	Z-score range	Performance band

Summary

The stanine (standard nine) scale is a nine-point normalized score system used widely in educational and psychological testing. This tool converts a percentile rank or z-score to the stanine equivalent and labels the performance band, so you can quickly interpret test results.

How it works

Enter a percentile rank (0–99) or a z-score (typically −4 to +4).
The tool maps your value to one of the nine stanine bands using the standard cutpoints.
The result shows the stanine number, the percentile range for that band, and the performance label.

Use cases

Interpret a student's norm-referenced test score reported as a stanine.
Convert a raw z-score from a psychological assessment into a stanine band.
Explain stanine-based reports to parents or students using plain language.
Cross-reference percentile ranks with stanine bands for program eligibility decisions.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu