Z-score calculator
Turn a value into a z-score and a percentile, or a percentile back into a value, on the normal curve.
The normal curve
Questions people ask
What is a z-score?
It is how many standard deviations a value is from the mean: z = (x − μ) ÷ σ. A z-score of 2 means two standard deviations above average.
How do I turn a z-score into a percentile?
Use the standard normal cumulative distribution. z = 1 is about the 84th percentile, z = 1.645 the 95th and z = 1.96 the 97.5th.