Psychology

Standard Score (Z-Score) Calculator

Convert raw scores to z-scores and percentiles

Last reviewed: How we build & verify
Z-Score
-1
Percentile
15.87%
Distance from Mean
1 SD
Position
Below Mean

z = (X - mean) / SD. The percentile assumes the scores follow a normal distribution; for skewed data it is only approximate. Use the population SD for norm-referenced tests (e.g. IQ: mean 100, SD 15).

What This Means For You

Get a personalized explanation of these results — what they actually mean for your situation, and how small changes would affect them.

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Frequently Asked Questions

No. Standard Score Calc is free, with no signup required, and nothing you enter leaves your browser.

Standard Score Calc is built on published formulas and reference ranges from established health sources. We revisit it periodically as guidance evolves; the "Last reviewed" date above shows when that last happened. If something looks wrong, tell us with the feedback button in the bottom-right corner.

Standard Score (Z-Score) | ExaCalc