Syntax
NORMDIST(x, mean, standard_dev, cumulative)
| Parameter | Description |
|---|---|
| x | Parameter of the NORMDIST function. |
| mean | Parameter of the NORMDIST function. |
| standard_dev | Parameter of the NORMDIST function. |
| cumulative | Parameter of the NORMDIST function. |
Examples
Cumulative probability
Formula
=NORMDIST(50, 45, 5, TRUE)
Returns 0.841 — 84.1% probability that a normally distributed value (mean 45, std dev 5) is below 50.
Defect rate
Formula
=1 - NORMDIST(10.2, 10, 0.05, TRUE)
If product spec is max 10.2mm and production mean is 10mm with std dev 0.05mm, returns the fraction exceeding spec.
Bell curve height
Formula
=NORMDIST(45, 45, 5, FALSE)
Returns 0.0798 — the PDF value at the mean, which is the peak of the bell curve.
Common Errors
#NUM!
Standard deviation is zero or negative.
#VALUE!
Non-numeric inputs.
Tips
Use NORM.DIST instead
NORMDIST is a compatibility function. NORM.DIST is the preferred modern version with identical behavior.
Empirical rule quick check
NORMDIST(mean+stdev, mean, stdev, TRUE) - NORMDIST(mean-stdev, mean, stdev, TRUE) always equals ~0.6827 (68.27% within 1 std dev).
Symmetry property
NORMDIST(mean-k, mean, stdev, TRUE) = 1 - NORMDIST(mean+k, mean, stdev, TRUE) for any k. The normal distribution is perfectly symmetric.
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