A/B Test Significance Calculator
Enter visitors and conversions to instantly see which variant really won
Use this calculator when you can't tell whether one variant is genuinely better or the difference is just noise. Enter the visitors and conversions for variant A and variant B, and a two-proportion z-test instantly returns the p-value and whether the result is statistically significant. Everything runs entirely in your browser, so none of your data is sent to a server. It's built for marketers, growth teams, and PMs who need a fast read on experiment results.
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🔒 Everything runs 100% in your browser. Your files and input are never uploaded to any server.
How to use
- Pick your confidence level (90%, 95%, or 99%).
- Enter the visitors and conversions for variant A (Control).
- Enter the visitors and conversions for variant B (Variation).
- Read the significance verdict, p-value, each variant's conversion rate, and the relative lift at the top of the screen.
FAQ
- Does a low p-value always mean B won?
- No. This tool only calls it a significant win when B's conversion rate is higher than A's AND the p-value falls below the threshold for your chosen confidence level. If B is underperforming A, it won't be reported as a win no matter how small the p-value is.
- What should I do if the result is 'not significant'?
- It usually means your sample size is too small or the true difference is minimal. Keep the test running to collect more data, then recalculate.
- Are the numbers I enter stored on a server?
- No. Every calculation happens instantly in your browser, and nothing is stored or transmitted.