A/B Significance Checker
Check whether an A/B result is statistically significant with a simple z-test.
Quick answer: enter your details below and click Check Significance — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
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How to use
- Enter visitors and conversions for variant A.
- Enter visitors and conversions for variant B.
- Click Check Significance.
About this tool
Enter visitors and conversions for variants A and B, and the tool compares rates with a two-proportion z-test approximation at the 95% level. This is a simplified statistical check, not a full experiment analysis, so use it as a guide and confirm important decisions with proper analysis.
Frequently asked questions
What does 95% mean here?
Roughly, a gap this big would appear by chance less than 1 time in 20 if there were no real difference.
Can I stop the test early?
Stopping the moment significance appears inflates false wins. Decide the sample size in advance and run to it.