FREE · MARKETING & SOCIAL MEDIA
A/B Test Significance Calculator.
Check whether an A/B test result is statistically significant, with the p-value, confidence interval, relative lift and a sample ratio mismatch check.
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How to use A/B Test Significance Calculator
Enter visitors and conversions for control and variant, then choose the confidence level and a one- or two-sided test.
How it works
z = (p_B − p_A) ÷ √(p(1 − p)(1/n_A + 1/n_B)) with the pooled rate p. The interval uses unpooled standard errors. A chi-square test flags splits that are unlikely under 50/50.
Example
500 conversions from 10,000 visitors against 580 from 10,000 is a +16 % lift with p = 0.0123: significant at 95 %.
Questions about A/B Test Significance Calculator
Is A/B Test Significance Calculator free, and do I need an account?
Yes. This tool is free to use in your browser without an account. Processing takes place on your device.
What are the limits and what should I check?
Two-proportion z-test for conversion rates; not for revenue per visitor or other averages. Do not stop a test early because it looks significant. Everything is calculated in your browser; nothing you type is uploaded. Review the result before using it in your work.
Is my input sent to a server?
Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.