A/B Test Significance Calculator

Find out if your test results are real or just random noise. Two-proportion z-test at 95% confidence level.

Test Your Results

Enter the visitor count and conversions for each variant. We'll tell you if the difference is statistically significant.

Control (A)
Variant (B)
Enter your test data
Fill in both variants and click "Run Significance Test"
Control Rate
Variant Rate
Relative Uplift
Confidence

A/B Testing Best Practices

1

Run Tests Long Enough

Wait for at least 1-2 full business cycles (usually 2 weeks minimum). Stopping early inflates false positive rates.

2

Test One Variable

Change only one element per test — headline, button color, layout. Multi-variable tests need much larger sample sizes.

3

Sample Size Matters

For a 1% baseline conversion rate, you need roughly 30,000 visitors per variant to detect a 10% relative improvement at 95% confidence.

4

Don't Peek Too Often

Checking results daily and stopping when you see significance leads to inflated false positives. Set your sample size target upfront.

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A/B testing is where small changes turn into big revenue. We design, run, and analyze tests across landing pages, ads, and funnels. 30-minute call, no strings.