# Effect Size Calculator Calculate Cohen d, Hedges g, Cohen h for proportions, or correlation r effect sizes from summary statistics > Canonical page: https://elysiatools.com/en/tools/effect-size-calculator - **Category:** Math & Numbers - **Keywords:** effect size, cohen d, hedges g, cohen h, correlation r, calculator ## Overview The Effect Size Calculator is a statistical utility designed to compute standardized effect sizes directly from summary statistics. Whether you need to calculate Cohen's d or Hedges' g for mean differences, Cohen's h for proportions, or evaluate correlation r, this tool provides precise effect size values and qualitative magnitude interpretations to help you understand the practical significance of your data. ## Inputs - **Effect Type** (select) - **Group 1 Mean** (number) - **Group 2 Mean** (number) - **Group 1 Standard Deviation** (number) - **Group 2 Standard Deviation** (number) - **Group 1 Size** (number) - **Group 2 Size** (number) - **Proportion 1** (number) - **Proportion 2** (number) - **Correlation** (number) - **Decimal Places** (number) ## When to use - When comparing the means of two independent groups to determine the standardized difference. - When evaluating the practical significance of a difference between two proportions in A/B testing or survey results. - When converting summary statistics into standardized effect sizes for meta-analyses or academic research reports. ## How it works - Select your desired effect type: Cohen's d, Hedges' g, Proportion h, or Correlation r. - Input the required summary statistics, such as group means, standard deviations, sample sizes, or proportions. - Specify the number of decimal places for your desired output precision. - The calculator instantly computes the effect size and provides a qualitative magnitude interpretation (e.g., small, medium, or large). ## Use cases - Academic researchers reporting the practical significance of experimental results in peer-reviewed journals. - Data analysts conducting meta-analyses to standardize and compare results across multiple independent studies. - A/B testing practitioners evaluating whether a statistically significant difference in conversion rates is practically meaningful. ## Frequently asked questions ### What is the difference between Cohen's d and Hedges' g? Cohen's d calculates the standardized mean difference, while Hedges' g applies a correction factor that provides a less biased estimate for small sample sizes (typically under 20). ### How do I interpret the magnitude of the effect size? The tool automatically provides a magnitude label based on standard statistical conventions, such as 0.2 for small, 0.5 for medium, and 0.8 for large effects in Cohen's d. ### Can I calculate effect sizes without raw data? Yes, this calculator is specifically designed to work with summary statistics like means, standard deviations, and sample sizes, requiring no raw dataset. ### What is Cohen's h used for? Cohen's h is used to measure the effect size between two independent proportions, helping to determine if the difference between two rates or percentages is practically meaningful. ### How many decimal places can I calculate? 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