Experiment Sample Size Calculator

Estimate how much traffic a test needs.

Calculate sample size from your baseline conversion rate and minimum detectable lift.

Experimentation

Estimate required sample size

Set the baseline, minimum lift, confidence, and power.

Baseline conversion %Minimum relative lift %ConfidencePowerTotal variants

Baseline5.00%

Target rate5.50%

Per variant31,234

Total sample62,468

Uses a two-sided normal approximation for two independent proportions with equal allocation. Real experiments may need more traffic because of seasonality, variance, multiple comparisons, instrumentation loss, or stopping rules.