A/B Test Calculator
Test statistical significance of A/B test results.
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Enter the number of visitors and conversions for each variant. The calculator uses a two-proportion z-test to determine if the difference in conversion rates is statistically significant at the 95% confidence level.
About This Calculator
A/B testing (split testing) compares two variants to see which performs better. This calculator uses a two-proportion z-test to determine if the observed difference in conversion rates is due to chance or a real effect. A statistically significant result (p < 0.05) means you can be confident the difference is real.
Frequently Asked Questions
How many visitors do I need?
Generally 1,000+ per variant for small effect sizes. Use the sample size calculator to determine the exact number based on your expected conversion rate and minimum detectable effect.
What is lift?
Lift is the relative improvement: (Rate B - Rate A) / Rate A * 100%. A 20% lift means variant B converts 20% better than A.
Can I test more than two variants?
This calculator handles A/B (two variants). For more variants, you need corrections for multiple comparisons (like Bonferroni) to control the false positive rate.