Minimum Detectable Effect (MDE) Calculator

Find the smallest effect size your A/B test can reliably detect given your sample size, baseline rate, and desired statistical power.

Baseline conversion rate

Current conversion rate (%)

%

Traffic

I know my daily visitors and planned test duration I'll enter sample size per variant directly

Average daily visitors to the test page

Planned test duration (days)

Sample size per variant

Test structure

Number of variants (excluding control)

Test type

Two-tailed (recommended default) One-tailed (improvement only)