Free tool
Before you launch an experiment, find out how many visitors each variant needs so the result is actually trustworthy. Enter your numbers and the calculator updates instantly, all in your browser.
FAQ
This tool uses the standard two-proportion formula based on your baseline conversion rate, the minimum detectable effect, your chosen confidence level, and statistical power to estimate the visitors needed per variant.
The minimum detectable effect is the smallest relative change in conversion rate you want the test to be able to detect reliably. Smaller effects require larger samples.
Lower baseline rates, smaller effects, higher confidence, and higher power all increase the sample size required to avoid false positives and false negatives.
Related
PulsePanda pairs your experiments with session replay, heatmaps, funnels, and feedback so you understand the why behind the win.
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