A/B sample size calculator
Estimate equal group sizes for a two-sided comparison of two conversion rates.
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Your result
Add your inputs, or try the example, to see your result here.
An approximation for independent binary outcomes; small counts may need exact methods.
How to use this tool
- Use the normal approximation for equal-size groups, a two-sided alpha, and entered power.
- Round the result up per variant.
What the result tells you
- An approximation for independent binary outcomes; small counts may need exact methods.
- Account separately for multiple testing and sequential peeking.