Effect Size Calculator (Cohen's D) for T-Test

Effect Size Calculator - Determine the Effect Size

Effect Size Calculator (Cohen’s d) for T-Test, This calculator allows you to determine the effect size, specifically Cohen’s d, when conducting a t-test. Cohen’s d is a commonly used measure of effect size that quantifies the difference between two means. 

Effect Size Calculator (Cohen's D) for T-Test

Cohen's d by automating the computation based

It provides valuable information about the magnitude of the difference between groups or conditions, helping researchers and practitioners interpret the practical significance of their findings. Our calculator simplifies the process of calculating Cohen’s d by automating the computation based on the provided data. 

Formula for Calculating Cohen's d for T-Test

Certainly! The formula for calculating Cohen’s d for a t-test is as follows:

Cohen’s d = (M1 – M2) / SDpooled


  • M1 is the mean of Group 1
  • M2 is the mean of Group 2
  • SDpooled is the pooled standard deviation

The pooled standard deviation (SDpooled) is calculated as:

SDpooled = sqrt(((n1 – 1) * SD1^2 + (n2 – 1) * SD2^2) / (n1 + n2 – 2))

Once you have the M1, M2, SD1, SD2, n1, and n2 values, you can substitute them into the formulas above to calculate Cohen’s d. Remember that Cohen’s d represents the standardized difference between the means of the two groups, providing an estimate of effect size.

Note: The formula assumes equal sample sizes for both groups in the t-test. If your study design involves unequal sample sizes, you may need to modify the formula accordingly.

How to use the Calculator

Enter the means and standard deviations:

– Group 1 Mean (M1):

Enter the mean value of Group 1.

– Group 2 Mean (M2):

Enter the mean value of Group 2.

– Group 1 Standard Deviation (SD1):

Enter the standard deviation of Group 1.

– Group 2 Standard Deviation (SD2):

Enter the standard deviation of Group 2.

Select the sample size and type:

– Sample Size: Specify the sample size for each group (assuming equal sample sizes).
– Sample Type: Choose between “Independent” or “Paired” samples based on your study design.

Click the “Calculate” button:

Once you have provided the necessary information, click the “Calculate” button to obtain the Cohen’s d value.

4. Interpretation of Cohen’s d:
Cohen’s d values can be interpreted as follows:
– Small effect: d ≈ 0.2
– Medium effect: d ≈ 0.5
– Large effect: d ≈ 0.8

Please note that effect sizes are not dependent on sample size, making them useful for comparing studies with different sample sizes.

Correctness or Applicability of the Results in Cohen's d Calculator

Cohen’s d Calculator provided by “Your Calculator World” is designed to assist users in computing Cohen’s d value quickly and easily. While we strive for accuracy, we cannot guarantee the correctness or applicability of the results obtained from this calculator. Understanding the underlying assumptions and limitations of effect size calculations and seeking expert advice when interpreting the results for your specific research or study is essential.

Happy calculating!

Start using our Cohen’s d Calculator today to enhance your understanding of the practical significance of your research findings and facilitate the interpretation of t-test results. Happy calculating!

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