# Inverse Cumulative Standard Normal Probability Calculator

Instructions: Compute the inverse cumulative score for the standard normal probability distribution. Provide a cumulative probability $$p$$ (a value on the interval [0, 1]), and the solver will find the z-value $$z$$ so that $$\Pr(Z \le z) = p$$. Cumulative Probability ($$p$$)

This Inverse Cumulative Standard Normal Probability Calculator will compute for you a score $$z$$ so that the cumulative standard normal probability is equal to a certain given value $$p$$. Mathematically, we find $$z$$ so that $$\Pr(Z \le z) = p$$.

Example: Assume that $$Z$$ has a standard normal distribution variable. Let us assume we want to compute the $$z$$ score so that the cumulative normal probability distribution is 0.89. The z-score associated to a cumulative probability of 0.89 is

$z_c = \Phi^{-1}(0.89) = 1.227$

This value of $$z_c = 1.227$$ can be found with Excel, or with a normal distribution table. Follow this link to compute normal probabilities

For a more general normal distribution, you can use this cumulative distribution grapher for generic normal distributions to instead compute cumulative values.

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