A/B Test Significance Calculator: Is Your Result Real or Noise

Enter the visitors and conversions for your control and your variant, and this returns the p-value, the confidence level, and the observed lift, so you can tell a real result from random noise. A higher percentage is not a winner on its own; it only counts once it clears the significance threshold.

This uses a two-proportion z-test, the standard method behind most A/B testing dashboards. The p-value is the probability of seeing a difference this large if the variant were actually no different from control. A small p-value means that fluke is unlikely, so the result is worth trusting. A two-sided test is the honest default; only use one-sided if you decided the direction before the test ran.