basic

Cohen's h Effect Size Between Two Proportions Calculator

h = 2·arcsin(√p₁) − 2·arcsin(√p₂).

Compute Cohen's h, the standardised effect-size between two proportions. h = 2·arcsin(√p₁) − 2·arcsin(√p₂). Interpretation: |h| ≈ 0.2 small; 0.5 medium; 0.8 large. Symmetric, sample-size-free; used to power tests for difference of two binomial proportions.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

h = 2·arcsin(√p₁) − 2·arcsin(√p₂).

In depth

Compute Cohen's h, the standardised effect-size between two proportions. h = 2·arcsin(√p₁) − 2·arcsin(√p₂). Interpretation: |h| ≈ 0.2 small; 0.5 medium; 0.8 large. Symmetric, sample-size-free; used to power tests for difference of two binomial proportions.