Experiment Duration Estimator

Calculate How Long to Run Your A/B Test

Parameters

users/day
%
%
control + test(s)
α (two-tail)
1 - β
Tip: For multi-variant tests, the calculator accounts for the Bonferroni correction (more stringent significance level). Use 2 variants for standard A/B tests.

Results

Recommended Duration
days to run experiment
Total Sample Size
Per Variant
Visitors Needed Per Day
Percentage of daily traffic

Duration vs Sample Size

The chart shows how sample size requirements decrease as you increase experiment duration. Longer tests allow sequential monitoring with lower Type I error risk.

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