Sample Size and Test Duration Calculator

This calculator combines everything from the single-purpose calculators below to provide you with a useful estimation tool you can use for planning your experiments.

What it does

Given your baseline conversion rate, desired Minimum Detectable Effect (MDE), confidence level, and statistical power, this calculator estimates how many users you'll need in each variant to detect a meaningful effect.

Why it's useful

It not only computes the required sample size per variant. It also factors in your available daily traffic and number of variants to estimate how long the test will take to run.

What you'll see

In addition to your exact input values, it generates a comparison table that shows how sample size and duration change as the MDE increases or decreases by 5%, 10%, 25%, 50%, and 100%. This gives you a practical sense of the tradeoffs between sensitivity, traffic, and test duration.

Use this calculator to make better decisions about:

• Whether your current traffic supports your planned test
• How long it will take to reach significance
• Whether your MDE is realistic given your constraints
• What the sample size would be for more aggressive or more conservative lifts