Estimate the participants you need to detect a real effect. Choose a design, enter your assumptions, and read the derivation — no sign-up required.
Study inputs
e.g. control event rate
e.g. treatment event rate
Pooled SD, assumed equal across groups
1 = equal groups
Inflates the requirement to preserve power
—
Total participants
Enter your assumptions to see the required sample size.
Formula used
—
Method. These calculations use standard normal-approximation formulae for hypothesis tests of proportions and means. For small samples, rare events, survival endpoints, cluster designs, or non-inferiority margins, treat these as a starting estimate and confirm with a statistician — or book a consult.