A/B Test Significance Calculator

Check if your A/B test result is real

An A/B test can show a difference that is just chance, and only a significance test tells you whether to trust it. This calculator runs a two-proportion test to check if your A/B result is statistically significant.

Why significance testing is essential

When you compare two variants and one converts better, the difference could be a real effect or just random variation, and the two look identical without a test. A significance test computes the probability that a difference this large would arise by chance if the variants were actually equal; if that probability is low enough, you can trust the result. Declaring a winner without this is the most common and costly mistake in A/B testing, because acting on noise wastes effort and can make things worse. The test is what separates a real improvement from a lucky sample.

A planning estimate

It runs entirely in your browser, so nothing you enter is uploaded, which matters when the input concerns your own business or security posture.

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