Which Calculator Do I Need?

How the tools fit together

Every experiment has two statistical moments. Before launch, you plan: the sample size calculator tells you how many visitors you need, the MDE & duration calculator tells you what your traffic can realistically detect and how long it will take, and the power calculator tells you what a given setup can actually catch. After (or during) the test, you evaluate: the A/B test calculator gives you the frequentist and Bayesian read of your results side by side, and the sequential testing calculator lets you monitor a live test as often as you like without inflating false positives.