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Sample Size Calculator

Determine how much traffic you need to confidently detect a drop in your core metrics.

JavaScript Required: This calculator requires JavaScript to compute the standard normal deviates for alpha and beta error levels.

Baseline Conversion Rate (%)

Minimum Detectable Effect (Relative %) The smallest relative change you want to be able to detect. 10% of a 4.5% baseline is a 0.45% absolute drop.

Statistical Significance (α)

Statistical Power (1-β)