When to use this calculator
The sign follows the order of the means. Interpretation depends on the subject and study design rather than a universal threshold.
Explore the descriptive statistics calculators for other questions in this topic. For a related calculation, use the Data Range Calculator: Find the difference between the largest and smallest values in a dataset.
PUTTING IT INTO PRACTICE
Cohens D: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| First mean | 80 |
| Second mean | 70 |
| Pooled standard deviation | 10 |
| Result | 1 |
- Check the input labels and enter the example values above.
- Apply the relationship: Cohen’s d = (first mean − second mean)/pooled standard deviation.
- The result is 1 , rounded for display.
How to interpret your result
This uncorrected standardised difference does not apply the small-sample Hedges correction.
The mean, median, range and standard-deviation tools accept variable-length lists with their limits stated. Choose a sample or population denominator appropriately. A summary statistic does not validate the sampling process or explain causation.
Frequently asked questions
Should I use sample or population standard deviation?
Use population deviation for the complete population being described. Use the sample form when estimating variability from a sample under suitable assumptions.
When is the cohens d calculator useful?
The sign follows the order of the means. Interpretation depends on the subject and study design rather than a universal threshold.
How do I use the cohens d calculator?
Enter first mean, second mean, pooled standard deviation. The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Cohen’s d = (first mean − second mean)/pooled standard deviation.
What should I check before using the result?
This uncorrected standardised difference does not apply the small-sample Hedges correction.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
Further reading
For background on this topic, see NIST: exploratory data analysis ↗. This is a topic reference, not an external review or endorsement of this tool.
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