Statistical Tool
A/B Test Significance Calculator
Know when a result is real — not just random variation. Stop making calls on gut feel.
Variant A (Control)
CTR2.50%
CVR8.00%
Variant B (Challenger)
CTR3.31%
CVR11.24%
Statistical Result
80%
Confidence Level
+40.5%
CVR Lift (B vs A)
⚠️ Approaching Significance — Need More Data
You're at 80% confidence — below the 95% threshold. Run the test longer or increase traffic. Calling it now risks a false positive.
Why Statistical Significance Matters
📉
Early Stopping
Most brands end tests too early. A test that 'looks like it's winning' at 70% confidence will flip 30% of the time. That's expensive guessing.
📊
Sample Size
Significance requires enough data. 50 conversions per variant is minimum. Less than that and your margins of error are massive.
🔄
One Test At A Time
Testing two things simultaneously (ad creative + landing page) makes it impossible to know what caused the result. Isolate variables.
⚖️
95% Is The Bar
Industry standard is 95% confidence. Anything less means you're making budget decisions on a coin flip. Patience in testing compounds.