Math Calculators
Z-Score Calculator
Find how many standard deviations from the mean.
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About the Z-Score Calculator
A z-score tells you how many standard deviations a value sits above or below the mean. Enter the value, the mean, and the standard deviation and the calculator returns the z-score using z = (x − μ) ÷ σ. It's a core statistics tool for standardizing data, comparing scores, and finding probabilities on the normal curve.
How to use the Z-Score Calculator
- 01Enter your value, mean, and standard deviation.
- 02Read the result instantly — it recalculates as you type.
- 03Adjust the numbers to model different scenarios.
Frequently asked questions
What is a z-score?
The number of standard deviations a data point is from the mean. z = 0 is exactly average; z = 2 is two standard deviations above.
What is a good z-score?
It depends on context. Roughly 95% of normally distributed data falls between z = −1.96 and z = +1.96.