Z-Score Calculator
Calculate the z-score (standard score) and its associated probability for a normal distribution.
About Z-Score
The z-score tells you how many standard deviations a value (x) is from the mean (μ): z = (x − μ) / σ. A z-score of 0 means the value equals the mean. ±1 means 1 SD away. Used widely in hypothesis testing, identifying outliers, and standardizing data for comparison.
Inputs
Raw Value (x)
Mean (μ)
Standard Deviation (σ)
Result
Z-Score
1.5
P(X < x) (Cumulative)
93.32%
P(X > x)
6.68%
P(|Z| < |z|) (Two-tailed)
86.64%
z = (85 − 70) / 10 = 1.5 — value is 1.5 standard deviations above the mean.