Pre-Experiment Power Calculator

Calculate the required sample size, detect the minimum effect size, and estimate how long your experiment needs to run. No account required.

Experiment Parameters

Baseline Conversion Rate5.0%

1%50%

Minimum Detectable Effect (relative)10%

1%50%

Significance Level (alpha)

Statistical Power

Number of Variants (including control)

Daily Users

Traffic Allocation100%

5%100%

Sample Size per Variant

Total: --

MDE (absolute)

baseline → treatment

Estimated Runtime

Enter daily traffic above

Sample size required per variant vs. relative effect size. Larger effects are easier to detect.

Adjust parameters above to see the power curve.

Get plain-English interpretation and suggestions for your experiment. Uses Claude AI when available, falls back to built-in templates.

Experiment Name (optional)

Primary Metric (optional)

Business Context (optional)

Want to understand the math?

Read our statistics guide on power analysis, MDE, and alpha.