What does a z-score of 1 mean?

A z-score of 1 means the value is exactly one standard deviation above the mean — at approximately the 84th percentile.

What is a good z-score?

Z-scores between -2 and +2 are considered normal. About 95% of data falls within ±2 standard deviations from the mean.

How is z-score used in real life?

Z-scores are used in standardized testing (SAT, GRE), quality control, medical reference ranges, and financial risk analysis.

Z-Score Calculator

Quick answer: Enter a value, mean, and standard deviation to get the z-score and percentile.

A z-score tells you how many standard deviations a value is from the mean. Enter the value, population mean, and standard deviation to find the z-score and its corresponding percentile.

Last reviewed: April 2026Report an error

Value

Mean

Standard Deviation

Z-Score

0.50

Z-score: 0.50, percentile: 69.15%.

Z-Score

0.50

Percentile

69.15%

How to Use This Z-Score Calculator

1Enter the data value you want to analyze.
2Enter the population mean (average).
3Enter the standard deviation.
4Read the z-score and corresponding percentile.

Frequently Asked Questions

: A z-score of 1 means the value is exactly one standard deviation above the mean — at approximately the 84th percentile.
: Z-scores between -2 and +2 are considered normal. About 95% of data falls within ±2 standard deviations from the mean.
: Z-scores are used in standardized testing (SAT, GRE), quality control, medical reference ranges, and financial risk analysis.

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Z-Score Calculator

How to Use This Z-Score Calculator

Frequently Asked Questions

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