z score Calculator


This calculator is from http://www.fourmilab.ch/rpkp/experiments/analysis/zCalc.html, with thanks going to John Walker.

Note that there is no closed form solution to come up with exact z-score cumulative probability values.  Therefore, the cumulative probability calculated from the z-score is an approximation. The calculators below calculate to six decimal places of accuracy, which is more than adequate for most purposes.

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Calculate cumulative probability p from z

One of the most common probability calculations is determining, given the measured z value from an experiment or set of experiments, the cumulative probability. Enter the z value in the box below, press the Return key or the Calculate button, and the probability will appear in the Q box.

Given z =

The cumulative probability, p, is:


Calculate z from cumulative probability p

To determine the z score indicating a cumulative probability p, enter p in the box below and press the Return key or the Calculate button.
Given cumulative probability p =

The z value is:


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