A/B Test Significance Calculator

Is variant B really better, or is it just noise? Everything runs in your browser — no data leaves this page.

1. Compare results

Visitors A Conversions A Visitors B Conversions B

2. Plan a test

Baseline conversion (%) Minimum lift to detect (%) Daily visitors

Two-tailed two-proportion z-test, 95% confidence, 80% power. Source code on GitHub · MIT license.