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A/B Test Calculator

Plan your experiments with statistical confidence

Free online A/B test calculator. Compute the Minimum Detectable Effect (MDE) you can measure with a given sample size, or find out how many visitors you need to detect a specific conversion lift. Supports absolute and relative MDE, one‑tailed and two‑tailed hypothesis tests.

MDE Calculator

Total Sample Size

Total visitors across both groups (control + treatment)

Baseline Conversion

e.g. 0.2 = 20%

Significance Level (α)

e.g. 0.05 = 5%

Statistical Power (1−β)

e.g. 0.8 = 80%

Two-tailed test

Sample Size Calculator

Baseline Conversion

e.g. 0.2 = 20%

MDE

e.g. 0.05 = 5pp absolute / 5% relative

Significance Level (α)

e.g. 0.05 = 5%

Statistical Power (1−β)

e.g. 0.8 = 80%

Two-tailed test Relative MDE

Results

Built with FastAPI & SciPy Created by nktnlx · Connect on LinkedIn