The z-score is 1.5, approximately the 93.32nd percentile under a normal model.
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Z-Score Calculator
Compare one observation with a population mean and standard deviation, then see its position on a normal curve.
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No account. Formula and assumptions are shown below.
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Z-score details
Formula & disclaimer
Z = (Observed Value β Mean) Γ· Population Standard Deviation
View assumptionsFormula reviewCalcs at Hand Editorial TeamVerified 31 August 2026 Β· automated checks included
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Projection
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How to read this result
Three useful checks, kept deliberately short.
An observation of 85, mean of 70 and standard deviation of 10: Subtract the mean Β· Divide by the standard deviation Β· Estimate the normal percentile.
The percentile estimate assumes an approximately normal distribution.
Formula and assumptions
Z = (Observed Value β Mean) Γ· Population Standard DeviationA positive z-score is above the mean and a negative z-score is below it.
Keep in mind: Use the percentile only when a normal-distribution model is appropriate for the data.
Produced byCalcs at Hand Editorial Team
Last formula check31 August 2026
Review methodKnown examples + boundary cases
Editorial and correction policy β