Free tools
Free A/B testing calculators
The two calculations every test depends on, free and with no signup. Use them whether or not you use Atchoo.
A/B test significance calculator
Paste your visitors and conversions for each variant and find out whether your result is real or noise, with a plain-English verdict.
Open calculatorA/B test sample size & duration calculator
Enter your baseline conversion rate and the lift you want to detect to see how many visitors you need, and how many days that realistically means.
Open calculatorNot sure which one you need? Use the sample size calculator before you start a test, and the significance calculator once you have results. Our guide to statistical significance explains the ideas behind both.