Enter two groups of numbers, then click Calculate.

The Mann-Whitney U test (also called the Wilcoxon rank-sum test) is a nonparametric statistical test used to compare two independent groups when the data is not normally distributed. It tests whether one group tends to have larger values than the other. The test ranks all observations from both groups combined, then compares the sum of ranks between the groups. The U statistic is calculated as U = n₁·n₂ + (n₁·(n₁+1))/2 − R₁, where n₁ is the size of group 1 and R₁ is the sum of ranks in group 1. The test statistic is then converted to a z-score and p-value for significance testing. This calculator is widely used in medical research, psychology, biology, and social sciences when the assumptions of the t-test are not met.

1. Enter the values for Group 1 in the first text area (comma or space separated).
2. Enter the values for Group 2 in the second text area.
3. Both groups must have at least 2 values each.
4. Click Calculate Mann-Whitney U to run the test.
5. The result shows rank sums, U statistic, z-score, and p-value.
6. The interpretation tells you if the groups are significantly different.
7. Click Reset to restore default example values.