AB Tester — Experiment Calculator & Tracker

🧮 A/B Test Significance Calculator

Confidence Level 95%

A Control

Visitors / Sample Size

Conversions / Successes

Conversion Rate

3.00%

B Variant

Visitors / Sample Size

Conversions / Successes

Conversion Rate

3.70%

Conversion Rate Comparison

A: 3.00%

B: 3.70%

Calculating...

—

Probability B beats A (Bayesian)

50%

0% — A wins 50% — Toss-up 100% — B wins

📐 Sample Size Calculator

Calculate how many visitors you need per variant to detect a given lift with statistical significance.

Baseline Conversion Rate (%)

Minimum Detectable Effect (%)

Relative lift you want to detect (e.g. 20% = detect 3% → 3.6%)

Statistical Power (%)

Confidence Level (%)

Daily Traffic (optional)

Variants

—

visitors per variant

📊 Common Benchmarks

Metric	Typical Range	Good Lift	Great Lift
Landing Page CTR	2-5%	+10-20%	+25%+
Email Open Rate	15-25%	+5-10%	+15%+
Signup Conversion	1-5%	+15-25%	+30%+
Checkout Conversion	2-4%	+5-10%	+15%+
Feature Adoption	10-30%	+10-15%	+20%+