Power analysis calculator
Find the sample size per group you need to detect a real difference in an A/B test, experiment or survey comparison. Free, instant and no sign-up.
Your test
Your result
64
Two-sided test with equal group sizes.
128
Across both groups.
What is a power analysis calculator?
A power analysis calculator tells you how many responses each group needs so a test can reliably detect an effect of a given size. Choose your significance level, power and effect size, and it returns the sample size per group for comparing two means (Cohen's d) or two proportions.
A/B testing forms
Know how many responses each form version needs before you pick a winner.
Experiments and studies
Plan group sizes so your study can detect the effect you care about.
Compare survey groups
Check if you can compare satisfaction between segments or time periods.
Avoid wasted effort
Stop underpowered tests early and oversized ones from wasting time.
Ready to collect your responses?
Build a beautiful form with BeeForm, share it, and track responses as they come in.