● Experimentation
A/B Test Statistical Significance Calculator
Enter the visitors and conversions for your control and variation to see whether the difference is real — with confidence, p‑value, relative uplift and the probability your variation wins.
| Visitors | Conversions | |
|---|---|---|
| Control | ||
| Variation |
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%
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Free, no signup — used by 40,000+ marketers to validate test results before shipping.
Control rate
Variation rate
Relative uplift
variation vs control
Chance to win
variation is better
How the two rates compare
Each curve is the plausible range for that version's true rate. The less they overlap, the more real the difference.
Control
Variation
Method: confidence and p‑value use a two‑proportion z‑test (one‑sided for the “Better” objective, two‑sided otherwise). Chance‑to‑win uses a Bayesian Beta‑Binomial simulation with uniform priors. Sample‑size estimate targets 80% power at your chosen confidence.