Free interactive student tool
Free Z-Score Calculator
Free Z-Score Calculator. Raw-score and probability modes; link into confidence interval and p-value tools.
Immediate resultNo sign-up requiredTransparent methodOptional email copy
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z = (x − mean) ÷ standard deviation
How this tool reaches its result
A z score expresses how many standard deviations an observation lies from the mean.
z = (x − mean) ÷ standard deviation
Worked context
How to interpret the output
A value of 85 in a distribution with mean 70 and SD 10 has z = 1.50.
Important limitation
What the result cannot decide for you
A z score does not make a skewed distribution normal.