Sample size for Comparison of means

Determine the required sample size for an independent-samples t-test. The test assesses whether the means of two independent groups differ by a clinically meaningful amount.

Input
Type I error - Alpha:
Type II error - Beta:

Difference:
Standard deviation group 1:
Standard deviation group 2:
Ratio of sample sizes in Group 1 / Group 2:
Result
Number of cases required in group 1:
Number of cases required in group 2:
Total sample size (2 groups together):

For details, see the MedCalc manual: Sample size: Comparison of two means.

How to cite this page

MedCalc Software Ltd. Sample size for Comparison of means. https://www.medcalc.org/en/calc/sample-size-comparison-of-means.php (Version 24.0; accessed October 11, 2026)

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