Find the z-score of a value and the percentile it corresponds to on a normal distribution. Enter the value, mean, and standard deviation.
Z-Score
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SDs from the mean.Usage Tip
Roughly: z of 1 is the 84th percentile, z of 2 the 98th. About 95 percent of data lies within z of plus or minus 2.
THE MATH
z = (value − mean) ÷ standard deviation
Percentile from the standard normal distribution
Percentile from the standard normal distribution
A z-score says how many standard deviations a value is from the mean.
On a normal distribution it maps directly to a percentile.
On a normal distribution it maps directly to a percentile.
The standard deviation must be positive.
A positive z is above the mean, negative is below.
The percentile assumes a normal distribution.
A positive z is above the mean, negative is below.
The percentile assumes a normal distribution.