Binomial probability calculator
Find the probability of a number of successes in n independent trials with constant success probability p.
Probabilities around k
| Successes k | P(X = k) |
|---|---|
| Fill in the fields above — the result is computed on this page. | |
How to use this page
- Choose exact, at most or at least.
- Enter n, p and k.
- Compare the point probability with the two tails.
What this page does not do: The model does not fit dependent trials or trials whose success probability changes.
Further reading
The binomial distribution models the number of successes in a fixed number of independent trials. Every trial must have the same success probability.
The calculator returns the point probability and both tails from one set of inputs.
Frequently asked questions
Should p be entered as a percentage?
Enter a number from 0 to 1, such as 0.2 for 20%.
How is this different from a binomial test?
This page calculates the distribution of successes. A binomial test evaluates a hypothesis about p from observed data.
See also
ACF and PACF autocorrelation calculator
Calculate ACF and PACF across time-series lags. Review the chart, reference bounds and coefficient table.
Adjusted R-squared calculator
Convert R² to adjusted R² using the number of observations and predictors in a regression model.
Beta distribution calculator
Calculate beta density, CDF, upper tail and quantile together with its mean and variance.