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Sample Size Calculator

Determine required sample size for your A/B test

Quick Start: Choose a Scenario

Inputs

Configure your experiment parameters

5.0 %

Your current conversion rate before the experiment

Minimum Detectable Effect (MDE)
Selected: +5.0%

MDE is the minimum relative improvement you want to detect. A 5% MDE on an 8% baseline means detecting a change to 8.4%.

Statistical Power
Selected: 80

Enter your daily visitors to estimate runtime

Sample Size per Variant

0

At your baseline of 5.0%, detecting a 5.0% relative uplift (to 5.25%) requires ~122.1K users per variant.

Total Sample Needed

0 visitors

Combined sample across both variants (control + treatment)

Summary

Baseline rate 5.0%
Minimum detectable effect +5.0% relative
Expected variant rate 5.25%
Statistical power 80%
Confidence level 95%

These tools are built with care, but we can't guarantee accuracy for every scenario. If something seems off, please reach out at [email protected] — we'd love to hear from you. We hope these tools help you run better experiments!