Free Tool
Effect Size Converter
Convert between Cohen's d, Hedges' g, correlation r, and odds ratio using standard meta-analysis formulas.
These conversions use standard approximations (Borenstein et al., Introduction to Meta-Analysis), which assume roughly normally distributed outcomes and reasonably balanced group sizes. They're a solid starting point, not a substitute for computing effect sizes directly from your primary study data where possible, especially for a published meta-analysis.