A/B Test Calculator

A two-proportion z-test — the standard method for comparing conversion rates between two independent groups (control A vs. variant B). It computes a z-score and flags results significant if |z| exceeds 1.96 (the 95% confidence threshold).

The tool reports significant at 95% confidence when the z-score's absolute value is above 1.96 — meaning there's less than a 5% chance the observed difference is due to random variation alone.

Keep running the test and collecting more visitors/conversions per variant; small sample sizes produce noisy results, and a promising-looking lift can disappear (or reverse) as more data comes in.

Yes — both tools run the identical two-proportion z-test on the same four inputs (conversions and visitors for A and B). They're offered under two names for people searching either term, but the calculation is exactly the same.