F Distribution Calculator
Calculate F distribution probabilities, critical values, and p-values for ANOVA and variance ratio tests with interactive charts.
The F distribution is the ratio of two independent chi-squared variables divided by their degrees of freedom. It is the basis for ANOVA F-tests, regression significance tests, and comparisons of variances between populations.
Use this calculator to find F critical values for a given significance level, compute p-values from observed F statistics, and visualize how the two degrees-of-freedom parameters control the shape of the distribution.
Launch the F Distribution workspace to plot the curve, inspect PDF/CDF behavior, and compute quantiles and interval probabilities.
Open Interactive Interval ProbabilityWhen do I use the F distribution?
Use it for ANOVA to compare means across groups, for testing whether two population variances are equal, and for overall significance tests in regression analysis.
What do the two degrees of freedom represent?
d1 (numerator) is typically the degrees of freedom for the between-group variation, and d2 (denominator) is for the within-group variation. In regression, d1 is the number of predictors and d2 is n minus the number of parameters.
How do I find the F critical value for ANOVA?
Set d1 to the number of groups minus 1, d2 to the total sample size minus the number of groups, and the quantile to 1 − α. The resulting value is the critical F value.