Free tool

Sample Size Calculator

Calculate your study sample size with the full formula, the values used and their basis — ready to paste into your Methods section.

Study design

Branch / speciality (optional)

Research topic

Use standard values (recommended)

Enter my own values

Prevalence must come from the literature for this specific topic, not a generic default. Fetch a topic-specific estimate, or enter your own from a paper you trust.

Expected Prevalence (%)

Margin of Error (%)

Confidence Level (%)

Attrition buffer (%)

These calculations follow standard published formulas. Always confirm the inputs and the final number with your guide or a statistician.