Fisher’s Exact Test Calculator
Enter the four cell counts of a 2×2 contingency table to get the exact two-tailed p-value from Fisher’s exact test.
What Fisher’s exact test does
Fisher’s exact test checks whether two categorical variables are related, using a 2×2 table of counts. Unlike a chi-square test, it calculates an exact p-value directly from the hypergeometric distribution instead of relying on a large-sample approximation, which makes it especially reliable for small sample sizes.
How this calculator works
Enter the four cell counts from your table: how many cases fell into each combination of group (A or B) and outcome (1 or 2). The calculator sums the probabilities of every possible table with the same row and column totals that is at least as extreme as yours, giving a two-tailed p-value. It also reports the odds ratio, a measure of how much more likely the outcome is in one group versus the other.
A p-value below 0.05 is commonly treated as evidence of an association between the two variables. This tool is for general educational and planning purposes and does not replace formal statistical review for research or clinical decisions.