Chi-square calculator

Calculate the chi-square (χ²) statistic for goodness of fit. Enter observed and expected frequencies.

Observed

Expected

χ² = Σ [(Oᵢ − Eᵢ)² / Eᵢ]

Where Oᵢ = observed frequency, Eᵢ = expected frequency for category i.

df = (number of categories) − 1. For a 2×2 table: df = (rows−1)(cols−1).

Large χ² → observed data differs significantly from expected. Compare with critical values at your significance level (typically α = 0.05).