The Excel GAMMA.DIST function returns the gamma distribution — either its probability density (PDF) or its cumulative probability (CDF) — widely used to model waiting times and skewed positive data.
Syntax
| Argument | Description | |
|---|---|---|
x | Required | The value at which to evaluate the distribution. Must be ≥ 0. |
alpha | Required | The shape parameter (α > 0). |
beta | Required | The scale parameter (β > 0). When β = 1 you get the standard gamma distribution. |
cumulative | Required | TRUE returns the cumulative distribution (CDF); FALSE returns the probability density (PDF). |
How to use it
The fourth argument flips GAMMA.DIST between two outputs. TRUE gives the cumulative probability that a value is ≤ x; FALSE gives the height of the density curve at x:
The shape alpha and scale beta together set the distribution's mean (α·β) and spread. The gamma family generalises several others: with alpha = 1 it becomes the exponential distribution, and the chi-squared distribution is a gamma with β = 2.
Inverse: to go the other way — from a probability back to an x value — use GAMMA.INV. GAMMA.INV(0.0681, 9, 2) returns about 10, undoing the CDF above.
GAMMA.DIST (Excel 2010+) replaces the legacy GAMMADIST function; both compute the same values but the dotted name is the current standard.
Try it: interactive demo
Pick a GAMMA.DIST example to see the formula and its result.
Practice workbook
Frequently asked questions
What does the cumulative argument do?
TRUE returns the cumulative distribution function (CDF) — the probability of a value at or below x. FALSE returns the probability density function (PDF) — the height of the curve at x.What are alpha and beta?
alpha is the shape parameter and beta is the scale parameter; both must be positive. The distribution's mean is alpha×beta. With beta = 1 you get the standard gamma distribution.How do I reverse GAMMA.DIST?
GAMMA.INV(probability, alpha, beta). It takes a cumulative probability and returns the x value that produces it — the inverse of GAMMA.DIST with cumulative = TRUE.Is GAMMA.DIST the same as the old GAMMADIST?
GAMMA.DIST (Excel 2010+) is the modern dotted name; GAMMADIST survives in the Compatibility category for older workbooks.Master functions like this in one day
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