A/B Test Calculator
Calculate the minimum sample size and duration for your A/B test.
Required Sample Size
13,915
per variant
Estimated Duration
28
days
What is A/B Testing and Why Do It?
A/B testing is a method of comparing two different versions of a web page or ad to measure which performs better. It allows you to statistically validate the impact of changes to landing pages, ad copy, CTA buttons, and visuals.
How is Sample Size Calculated?
This calculator determines the minimum sample size needed based on your current conversion rate, the minimum effect you want to detect, and your confidence level. The formula uses the two-proportion z-test statistical method. Enter your daily visitor count to also estimate the test duration.
Why is the Right Sample Size Critical?
A/B tests with insufficient samples lead to incorrect conclusions. A test ended too early might show a 'winning' variation that actually has no real effect. This calculator helps you determine the minimum traffic needed for statistically reliable results.
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