Free tool · Plan your study
Pick your study design from 30 epidemiological designs, enter a few numbers, and get the formula, the worked calculation, a sensitivity table and a ready-to-paste methods sentence.
✓ 100% free · ✓ No sign-up · ✓ Runs in your browser
Who this is for
Students and researchers writing a proposal, ethics application or methods chapter who need a defensible sample size without a statistician on call.
Watch it work
Follow the walkthrough — click any step to see it, or let it play.
Study design
Your assumptions
Required sample size
Methods sentence
Assuming a prevalence of 30%, a 5% margin of error and 95% confidence, the minimum sample was 323; allowing for 10% non-response, 359 participants will be recruited.
What you get
Paid help · when you want it
Our statisticians can take over this step for you — fully justified, checked and explained for your supervisor or reviewers.
FAQ
Thirty common epidemiological and clinical designs, from single proportions to cluster trials and diagnostic accuracy studies.
Each result shows the formula, inputs and references so it can be checked and cited.
Ask for expert help — we will calculate and justify it for your exact design.
Complete your workflow
Design your study and generate a realistic dataset to plan with.
Upload your data. Get publication-ready tables and figures.
Find real references and format them in any style — instantly.
Check how much of your writing reads as AI — sentence by sentence.