Sample Size Calculator

Use these calculators for clinical trials including superiority, equivalence and non-inferiority trials.

Calculators for clinical trials

What the calculators offer

This website provides on-line tools to estimate the sample size needed for a clinical trial. Sample size calculations are supported for the following trial designs and outcome types: 

  • Superiority, equivalence, non-inferiority trials for binary outcomes 
  • Superiority, equivalence, non-inferiority trials for continuous outcomes 

The information required as input from the user is clearly identified, as is the output generated by the program. The program does not have a calculator for time-to-event outcomes. The calculator does not provide the option of calculating the power, only the sample size.  However, the program clearly explains the difference between the different designs (superiority, equivalence, non-inferiority), and provides references and the citation for the service. 

Who it's for

Clinical investigators, statisticians 

Who created it

This site is run by sealed envelopeTM, a British company that provides access to online software applications for randomizing patients into clinical trials and recording their case report form data.