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Z-score Calculator

A z-score tells you how many standard deviations a value is above or below the mean.

How it works Report a problem

Normal Sigma Z

Dynamic Gaussian Position Analysis

About the Z-score Calculator

A z-score tells you how many standard deviations a value is above or below the mean.

How to use the Z-score Calculator

  1. Enter the Raw Value (X), the Mean (μ) and the Std Dev (σ).
  2. Press Solve Z-Position.

Formula and method

z = (x − μ) ÷ σ

Worked example

A score of 85 in a test with a mean of 70 and standard deviation of 10 has z = 1.5, above average.

Tips

  • About 68% of values lie within z = ±1 and 95% within ±2 in a normal distribution.
  • Z-scores let you compare values from different scales.

Frequently asked questions

What does a negative z-score mean?
The value is below the mean.