A/B Test Calculator

Calculate sample size for an A/B test.

Test Parameters

95% is the standard for most CRO tests.

%

The percentage of users who complete the desired action in the control variant.

%

The minimum relative change you want to detect. E.g.: 20% means detecting an increase from 5% to 6.00%.

/ giorno

The total visitors split between variant A and variant B (50/50).

Results

Valid
8156
Sample per variant
16.312
Total sample
17
Estimated days
+20%
Detectable relative lift
Control conversion5%
Detectable conversion6.00%
Confidence95%
Statistical power80%
Critical Z-score1.96

How to interpret results

  • Sample per variant: how many users must see each variant (A and B) before drawing conclusions.
  • MDE: minimum detectable effect. A 20% MDE on a 5% rate means detecting a change up to 6%.
  • Estimated days: calculated by dividing the total sample by the daily visitors entered.
  • Statistical power 80%: the test has an 80% probability of detecting a real effect when it exists.