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Beta distribution calculator

The beta distribution models continuous values from 0 to 1 and offers flexible shapes for proportions.

Selected calculation result: —

Fill in the fields above — the result is computed on this page.

x or quantile
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Density f(x)
—
P(X ≤ x)
—
P(X ≥ x)
—
Mean
—
Variance
—
Standard deviation
—

What do these numbers mean?
  • The mean is α/(α+β).
  • When α=β the distribution is symmetric around 0.5.

The model applies to continuous values from 0 to 1. The parameters are not automatically counts of successes and failures without a stated statistical model.

How do I use this page?
  1. Choose density, CDF, upper tail or quantile.
  2. Enter positive α and β.
  3. Provide x in [0,1] or probability q.

What this page does not do: The model applies to continuous values from 0 to 1. The parameters are not automatically counts of successes and failures without a stated statistical model.

Further reading

Theory — what is the beta distribution?

The beta distribution models continuous values between 0 and 1, making it a natural tool for describing proportions and probabilities. Parameters α and β control the shape of the curve — it can be symmetric, skewed, or concentrated near the middle or the edges of the interval. The density f(x) is not limited to values below 1 — it can exceed 1, since only the total area under the curve must equal 1. This distribution is often used as a prior in Bayesian analysis.

Frequently asked questions

Can f(x) exceed 1?
Yes. A density can exceed 1 while the total area under the curve remains 1.
When is beta uniform?
With α=1 and β=1 every value in [0,1] has the same density.

See also

← All calculators

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