Last updated September 2026
A/B testing needs more traffic than most marketers think.
And it’s not your total site traffic that counts. It’s the traffic eligible for the specific test you’re running.
This calculator estimates the eligible impressions a standard 50/50 A/B test needs, based on your current click-through rate, the improvement you want to detect, and your confidence level. It also estimates how long that sample size could take to reach at your current traffic.
Baseline CTR is your control’s current click-through rate. Minimum Detectable Improvement is the smallest relative lift you want the test to catch. A 20% improvement on a 2% CTR means testing whether the new version can hit roughly 2.4%.
Assumptions: 80% statistical power, 50/50 traffic split. Standard for fixed-horizon A/B test planning.
Numbers look unrealistic? Read How to A/B Test a Low-Traffic Website When Statistical Significance Is Unattainable.
Using SiteSqueeze? See how SiteSqueeze evaluates A/B tests and makes winner recommendations.
Note: This plans a fixed-horizon test. It won’t judge a test you’ve already run.