Growth maths · Free
A/B Test Sample Size & Duration
How many users a test needs and how long to run it.
Users per variant
31,234
Total users
62,468
Days to run
32
5 week(s)
Target conversion
5.50%
95% confidence, 80% power, two-sided test.
How to use it
- Enter your current conversion rate and the smallest lift worth detecting.
- Run the test for at least the suggested days, and full weeks.
What good looks like
- At least 1–2 full weeks to cover weekday and weekend behaviour.
- Decide the stopping date before you start — no peeking.
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