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Z-score calculator
How many standard deviations a value is from the mean, and the share of a normal distribution below it. Free, with no account or uploads.
Find a z-score
Type the value, the mean and the standard deviation.
Z-score
1.5
(85 − 70) ÷ 10. In a normal distribution 93.32% of values are below it and 6.68% above.
Sums and means are exact; worked out in your browser, and nothing you type is sent anywhere or kept.
A little help along the way
Follow these steps. Every option is explained underneath. Everything runs in your browser; nothing is sent anywhere or kept.
- Say what you want to knowDescribe your numbers, a z-score, or a z-table.
- Paste or type your numbersSeparated by commas, spaces or new lines, and say whether they are a sample or a whole population.
- Read the answerThe figure you came for first, then every measure, and the working under it.
Questions people ask
- How is a z-score worked out?
- (The value − the mean) ÷ the standard deviation: 85 with a mean of 70 and a standard deviation of 10 is 1.5.
- What share of values are below it?
- The page gives the share of a normal distribution below and above the z-score, to two decimal places as a percentage.
- Does it assume a normal distribution?
- The z-score does not; the shares below and above it do.
This page is the Statistics calculator, opened for this one job; every other tool it has is one press away. Each of its settings is explained on the Statistics calculator's own page.
Read the step-by-step guide