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

Enter your research topic above. NerdAI will automatically find and apply a topic-specific prevalence from published literature.

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.