Chi-Square Calculator
Enter observed and expected frequencies (same count, comma-separated). Expected values must be > 0.
Chi-Square Test — Formula
Goodness-of-fit formula
χ² = Σ (O − E)² / E
df = k − 1 (where k = number of categories)
Example: 4 categories, each expected 25
Observed: 25, 30, 20, 25 → χ² = (0 + 1 + 1 + 0) = 2, df = 3, p ≈ 0.57 (not significant)
