Free A/B Test Significance Calculator

Plug in your experiment numbers (or upload a CSV) and get p-values and confidence intervals for binary or continuous metrics. Plan your sample size before you start — rigorous statistics, no signup.

Built for modern experimentation

AB SHARK handles both conversion-rate tests (two-proportion z-test) and continuous metrics like revenue per user, time on site, or order value (Welch's t-test with Bessel-corrected sample variance). Use post-stratification to reduce variance on imbalanced segments — supported for binary and continuous outcomes alike. Plan sample size for either family before you launch, with the minimum detectable effect (MDE) in absolute or relative units.