How to use the inverse normal calculator
Find the value that matches a cumulative probability. Enter mean, standard deviation, cumulative probability in the fields above; the value, z-score are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- mu — Mean
- s — Standard deviation
- p — Cumulative probability
Worked example
With mean = 100, standard deviation = 15, cumulative probability = 0.95, the calculator gives value ≈ 124.6728; z-score ≈ 1.644854.
Frequently asked questions
What is the formula for the inverse normal calculation?
Value = mu+s × norminv(p). Z-score = norminv(p). Here mu is mean, s is standard deviation, p is cumulative probability.
What inputs do I need for the inverse normal (percentile to value) calculator?
You need mean, standard deviation, cumulative probability. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.