A/B Test Significance Calculator
Know if your results are real or just random noise. Plan how many visitors you need before you start — or evaluate whether a completed test has a real winner.
Add visitors and conversions for both Control (A) and Variation (B) to find out if your results are statistically significant.
How to Use This Calculator
Three modes for every stage of your testing workflow — plan before you start, evaluate once you have data, or compare multiple variants at once.
Choose your mode
Use "A/B Test" to check results you already have. Use "Plan Test" to figure out how many visitors you need. Use "Multi-variant" to compare 3 or 4 versions at once.
Enter visitors and conversions
Conversions can be any goal: purchases, sign-ups, clicks. Just make sure you use the same goal definition for both variants — mixing goals will give misleading results.
Set your confidence level
95% is the industry standard — it means you accept a 1-in-20 chance of a false positive. Use 99% for high-stakes changes like pricing; 90% for fast exploratory tests.
Read the colour-coded result
Green means a statistically significant winner. Red means the variation is significantly worse. Yellow means there's not enough data yet — do not declare a winner early.
Never stop tests early
Peeking at results and stopping when you see significance inflates false-positive rates dramatically. Decide your sample size in advance using "Plan Test" mode.
Plan before you test
Use "Plan Test" to calculate how many visitors you need. Enter your daily traffic to get an estimated test duration — and always run for at least one full week to avoid day-of-week bias.
Ready to build a testing programme that actually works?
Statistical significance is the floor, not the ceiling. Search Indicators connects your SEO, CRO, and testing data into one growth picture — so you know what to test and why it worked.
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