A/B Test Sample Size Calculator: How Many Visitors Do You Need?
· 4 min read
The most common A/B testing mistake isn't bad traffic or wrong goals — it's stopping the experiment too early.
Without calculating the required sample size before you start, you're likely to call a winner based on random noise and ship a change that has no real effect, or worse, a negative one.
This guide walks through the exact formula, a real worked example, and what to do when your traffic is too low.