Z-Score Calculator
Solve z = (x − μ) ÷ σ — enter a value, the mean and the standard deviation to see how many standard deviations it is from the mean.
Reviewed by the OmniCalc teamMethod verified 2026-07-01
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Z-score 3Show steps
- Subtract the mean: x − μ = 85 − 70 = 15.
- Divide by the standard deviation: z = (x − μ) ÷ σ = 15 ÷ 5 = 3.
How to use the z-score calculator
- 1Enter the value (x) you want to score.
- 2Add the distribution’s mean (μ) and standard deviation (σ).
- 3Read the z-score, and open Show steps to see the formula with your numbers.
The z-score in one line
A z-score counts how many σ a value is from the mean: positive means above the mean, negative means below, and 0 means exactly at the mean. In a normal distribution, about 95% of values fall between −2 and +2.
Frequently asked questions
What does a z-score tell you?
It tells you how many standard deviations a value sits from the mean. A z-score of +2 is two standard deviations above the mean; −1.5 is one and a half below it. A z-score of 0 means the value is exactly the mean.
Is a negative z-score bad?
No — the sign only shows direction. A negative z-score means the value is below the mean and a positive one means it is above. Whether that is good or bad depends entirely on what you are measuring.
What formula does this use?
The standard-score formula z = (x − μ) ÷ σ, where x is the raw value, μ is the population mean and σ is the population standard deviation. The calculator subtracts the mean, then divides by the standard deviation.