Enter a value along with the mean and standard deviation of its distribution to calculate its z-score and corresponding percentile.
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A z-score measures how many standard deviations a value is from the mean: z = (value − mean) ÷ standard deviation. This calculator then converts that z-score into a percentile using the standard normal cumulative distribution function, showing what percentage of values in a normal distribution fall below your entered value.
A negative z-score means the value is below the mean, a positive z-score means it's above the mean.
Yes, the percentile conversion assumes the underlying data follows a normal (bell-curve) distribution. The z-score itself is valid for any distribution, but the percentile figure is only accurate when that assumption holds.
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