What is the A/B Test Calculator?
The A/B Test Calculator compares conversion rates between two variants using a chi-squared significance test, telling you whether the difference is statistically reliable or could simply be random noise.
How to Use This A/B Test Calculator
- Enter the visitor count and conversion count for Variant A.
- Enter the visitor count and conversion count for Variant B.
- Review the conversion rates, relative improvement, and significance badge.
- Use the sample size calculator to plan how much traffic you need before launching your next test.
When Do You Need an A/B Test Calculator?
- Deciding whether a new landing page variant actually outperforms the original.
- Avoiding the mistake of declaring a "winner" too early based on a small sample.
- Planning the minimum traffic needed before starting a new test.
Frequently Asked Questions
What is statistical significance?
Statistical significance means the difference between two test variants is unlikely to be due to random chance. A common threshold is a p-value below 0.05, meaning there's less than a 5% probability the observed difference happened by chance.
How long to run an A/B test?
Run a test until you reach your pre-calculated minimum sample size, and for at least one full business cycle (typically 1-2 weeks) to account for day-of-week variation. Stopping early based on partial results often leads to false positives.
95% vs 99% confidence level?
A 95% confidence level accepts a 5% chance of a false positive and is the standard for most marketing tests. A 99% confidence level is stricter, reducing false positives but requiring a larger sample size and longer test duration.
A/B test vs multivariate test?
An A/B test compares two complete variants against each other. A multivariate test changes multiple elements simultaneously and tests every combination, requiring significantly more traffic to reach statistical significance for each combination.