Sample size calculator

You want to hit statistical reliability - fast.
Figure out how big your sample size needs to be with our ab test calculator.
No Mathematics PhD required.

When running A/B testing to improve your conversion rate, it is highly recommended to calculate a sample size before testing and measure your confidence interval.

This advice comes from old-fashioned industries (agriculture, pharmaceutical…) where it’s important to know your confidence level because it will define the experiment costs that we are looking to keep as low as possible.

This is what sample size calculators are used for. You are asked for the current success rate (conversion rate) and the size of the minimum effect to be measured. The result of the calculation is the population size needed to conclude from such an experiment.

This transposes badly in the “digital area” for three main reasons:

  1. Measuring conversions costs nothing (unlike in the industry).
  2. The number of visitors is a part of the problem (not the answer).
  3. The effect of variation is difficult to predict (in practice this is precisely the question you are asking yourself!).


This makes it very difficult to use sample size calculators. So, our data scientists @AB Tasty have developed a Minimum Detectable Effect calculator (MDE).

Just enter the number of visitors you have on your site and the conversion rate of the page you want to test!

Minimum Detectable Effect calculator

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Minimal Detectable Effect