Enter A/B or pre/post counts
Variant / Period A
Variant / Period B
For two independent groups or periods with binary outcomes.
Result
-
How to read the result
| Relative lift | How much B changed relative to A. |
|---|---|
| p-value | Smaller values indicate the observed difference would be less common under equal conversion rates. |
| p < 0.05 | Shown as Significant when the simple sample check is adequate. |
| Important | Statistical significance does not prove causation. |
Useful for
Landing-page CVR, CTA click rate, booking rate, meeting conversion, quote-to-close rate, store purchase rate, signup rate, retention rate, and other binary conversion KPIs.
For pre/post experiments, check traffic source, audience mix, pricing, promotion, staffing, weekdays, and seasonality before attributing the change to your intervention.
Planning a test instead?
Use your baseline CVR, traffic and available test window to estimate the smallest lift you can realistically detect.
Check A/B test feasibilityNeed to track experiments, not just calculate one?
Experiment Impact Lab saves up to 100 experiments locally, keeps notes and context, exports CSV, and creates an AI-ready review prompt.
One-time Excel download. See the product page for the current price and purchase requirements. No paid AI API is required.
Get Experiment Impact Lab — $12Simplified two-proportion z-test reference. Calculation runs in your browser; these numeric inputs are not submitted by the calculator to an application server.