Marketing Calculators

A/B Test Calculator: Significance and Sample Size

Check whether the conversion difference in your A/B test is significant (z-test, p-value) — or estimate in advance how much traffic each variant needs for the expected effect.

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What to measure
Variant A (control)
Variant B (test)
conversion rate A
conversion rate B
change (uplift)
p-valuetwo-sided z-test
confidence

Significance uses a two-sided z-test for proportions. The default threshold is 95%: if the p-value is below 0.05, the difference is unlikely to be random. Sample size uses the classic formula for comparing two proportions.

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