Cohens D Calculator


Calculating Cohen’s d is a statistical method used to measure the effect size of the difference between two groups. This calculation is essential in various fields, including psychology, education, and medicine. In this article, we’ll explore how to use Cohen’s d calculator, provide the formula, solve an example, address frequently asked questions (FAQs), and conclude with its significance.

How to Use

Using the Cohen’s d calculator is straightforward. Input the means, standard deviations, and sample sizes of two groups into the provided fields, then click the “Calculate” button to obtain the result.


The formula for calculating Cohen’s d is:

Where the Pooled Standard Deviation is calculated as:

Pooled Standard Deviation=

Example Solve

Suppose we have two groups, Group A and Group B, with the following characteristics:

  • Group A: Mean = 15, Standard Deviation = 3, Sample Size = 50
  • Group B: Mean = 18, Standard Deviation = 4, Sample Size = 50

Using the formula:

Cohen’s d≈−0.85


Q: What does Cohen’s d measure?
A: Cohen’s d measures the standardized difference between two means.

Q: What is considered a small, medium, or large effect size for Cohen’s d?
A: Typically, a Cohen’s d around 0.2 is considered small, 0.5 is medium, and 0.8 or above is large.

Q: Is Cohen’s d affected by sample size?
A: Yes, larger sample sizes tend to produce more reliable estimates of Cohen’s d.


Cohen’s d calculator provides a convenient way to quantify the effect size between two groups in various research and statistical analyses. By understanding how to use this tool and interpret its results, researchers can gain deeper insights into the significance of differences observed in their data.

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