F distribution calculator
Choose a calculation and enter numerator and denominator degrees of freedom.
How do I use this page?
- Choose CDF, upper tail or quantile.
- Enter d₁ and d₂.
- Provide x or a probability and read the result.
What this page does not do: The F distribution is one-sided and non-negative. A distribution result does not replace checking assumptions of the specific test.
Further reading
Theory — what is the F distribution?
The F distribution describes the ratio of two independent, appropriately scaled variances. It is used in analysis of variance, tests comparing variances between two groups, and in evaluating the overall quality of regression models. The shape of the distribution depends on two parameters — the numerator and denominator degrees of freedom — so calculating a probability requires both values. The F distribution's cumulative function is computed using the regularized incomplete beta function.
Frequently asked questions
Why are two df values needed?
What is the 0.95 quantile?
See also
A/B test calculator
Compare two proportions in an A/B test. Calculate conversion rates, difference, uplift, z score, p value and c
A/B test planning — sample size, MDE and duration
Plan a two-proportion experiment, estimate detectable effect and traffic duration.
ACF and PACF autocorrelation calculator
Calculate ACF and PACF across time-series lags. Review the chart, reference bounds and coefficient table.