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Z-Score Calculator

Calculate how many standard deviations a value sits from the mean, with percentile.

To calculate a z-score, enter a value, the population mean and the standard deviation. The z-score expresses how many standard deviations the value sits from the mean, and the percentile shows what proportion of a normal distribution falls below it.

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Runs entirely in your browser — nothing is uploaded
Cost
Free, unlimited, no sign-up

Frequently asked questions

What does a z-score of 2 mean?

The value sits two standard deviations above the mean. In a normal distribution that puts it above roughly 97.7% of the data, which is why 2 is a common threshold for flagging an outlier.

How to use the z-score calculator

  1. 1Set the value (x).
  2. 2Set the mean (μ).
  3. 3Set the standard deviation (σ).
  4. 4The result appears immediately — copy or download it.

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Put the working z-score calculator on your own site. It runs in your visitors' browsers exactly as it does here — free, no account, nothing uploaded.

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