Cramér's V Calculator
Effect size for a contingency table — chi-square, degrees of freedom, p-value and Cramér's V (with the phi coefficient for 2×2).
How it works
V = √[ χ² ÷ (n · (min(rows, columns) − 1)) ]; χ² = Σ (O − E)² ÷ E, E = row total × column total ÷ n
A chi-square test says whether two categorical variables are associated, but its size grows with the sample. Cramér's V rescales chi-square to a 0–1 effect size that is comparable across tables and sample sizes. For a 2×2 table it equals the phi coefficient. Thresholds shift with the smaller dimension — for df* = 1, 0.1/0.3/0.5 are small/medium/large; for larger tables the same V means a stronger association.
Worked example
A 3×3 table with n = 125: χ² = 47.6, df = 4, p < 0.0001, V = 0.44 — a medium-to-large association.
Frequently asked questions
V or the contingency coefficient?
Cramér's V reaches 1 for a perfect association in any table shape; Pearson's contingency coefficient cannot, so V is the better-behaved measure.
Does V have a direction?
No — it is always positive. Use the table itself (or odds ratios) to see which categories go together.
Related calculators
For education — check assumptions (sample size, distribution, independence) before using a test result in a real decision.