Online Tool Store
Effect Size Calculator
Enter the means and standard deviations of two groups to calculate Cohen's d effect size. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Result
Cohen's d = (Mean1 − Mean2) / pooled SD
Example shown — enter your own values to recalculate.
How it works
- Enter your values into the fields above.
- The result updates to reflect your inputs.
- Use the result to plan or document your work.
Enter the means and standard deviations of two groups to calculate Cohen's d effect size. Runs entirely in your browser.
FAQ
Is my data uploaded anywhere?
No. Effect Size Calculator runs entirely in your browser — nothing is sent to a server.
Is this tool free to use?
Yes, Effect Size Calculator is completely free with no sign-up required.
How accurate is the result?
The calculation follows the standard formula for this type of estimate; always confirm against project-specific specs for critical work.
Can I use this on mobile?
Yes, the tool is fully responsive and works on any device with a modern browser.
How we compare
| Feature | Online Tool Store | Manual calculation | Spreadsheet templates |
|---|---|---|---|
| Instant result | ✓ | Slow, error-prone | ✓ |
| Free, no sign-up | ✓ | ✓ | Often requires download |
Spreadsheet templates can go deeper for repeated project tracking. Effect Size Calculator gives a quick, free result for a one-off calculation.