Hedges' g Effect Size Calculator

Calculate bias-corrected standardized effect size for comparing two groups

Group 1 Mean:

Group 2 Mean:

Group 1 SD:

Group 2 SD:

Group 1 Sample Size (n₁):

Group 2 Sample Size (n₂):

About Hedges' g

Hedges' g is a bias-corrected version of Cohen's d, especially important for small samples.

Formula: g = d × (1 - 3/(4df - 1))

The correction factor approaches 1 as sample size increases.

Interpretation:

|g| < 0.2: Negligible
0.2 ≤ |g| < 0.5: Small
0.5 ≤ |g| < 0.8: Medium
|g| ≥ 0.8: Large