Z-Score Calculator

Instantly measure how far a value is from the mean.

💡 Enter a value, its mean, and the standard deviation. The result shows how many standard deviations the value is from the average.

Z-score: —

Z-score standardizes a value relative to the distribution.

Example 1 (Above the Mean)

Value (x): 85 Mean (μ): 70 Standard deviation (σ): 10 → Z-score = (85 − 70) / 10 = 1.5

Value (x): 60 Mean (μ): 70 Standard deviation (σ): 5 → Z-score = (60 − 70) / 5 = -2

Z = (x − μ) / σ

Where: x = value μ = mean σ = standard deviation

Z-scores convert raw values into standardized scores. This allows comparison across different datasets.

Z-scores help detect unusual observations, compare performance, and analyze probability in normal distributions.

The value is exactly equal to the mean.

Yes. Negative Z-scores indicate values below the mean.

An absolute value above 2 or 3 typically indicates an unusual observation.

It is most meaningful when data follows a normal distribution.