A/B Test Significance Calculator — free online
You ran an A/B test, version B got a few more sign-ups, and now you're staring at the numbers wondering: did B really win, or did it just get lucky? It's an easy thing to guess wrong about. We added a free tool that settles it — A/B Test Significance Calculator — right in your browser.
What it does
You type in the visitors and conversions for variant A and variant B. It shows the conversion rate for each side, the relative uplift between them, the p-value from a two-proportion z-test, and a plain-English verdict on whether B truly beat A or the gap is just noise. You can pick your confidence level (90, 95 or 99%) and choose a one-sided or two-sided test.
Nothing leaves your device
The whole thing runs in your browser. Your numbers aren't uploaded anywhere, nothing is saved, and there's no sign-up. Close the tab and it's gone.
How to use it
- Open A/B Test Significance Calculator and enter visitors and conversions for A and B.
- Pick a confidence level and whether the test is one-sided or two-sided.
- Read the verdict — rates, uplift, p-value, and whether the result is significant.
It's free with no limit. There are more small tools on the Apps page.