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Z-score Calculator

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Find how many standard deviations a value is from the mean, and its percentile.

Z-score 1.5
Z-score1.5
Percentile93.32%

What Is a Z-score?

A z-score tells you how many standard deviations a value is above or below the mean of its distribution. A z-score of 0 means the value equals the mean; positive scores are above the mean, negative scores are below it. Z-scores make it possible to compare values from different scales or distributions on the same footing.

z = x − μσ

Percentile

Assuming the data follows a roughly normal (bell-curve) distribution, the z-score can be converted into a percentile - the percentage of values that fall below your value. This calculator uses a standard normal approximation to estimate that percentile.