Research Sample Size Calculator
Work out a survey sample size.
Runs in your browser. Nothing is uploaded — your input is processed on this device and discarded when you close the tab.
Research Sample Size Calculator
How to use this tool
- Enter your details in the fields above.
- Press Generate to see the result.
- Use Load sample to try the worked example, or Clear to start again.
Worked example
For 95% confidence, a 0.05 margin of error and proportion 0.5, the uncorrected size is 385. With a population of 1000, the finite-population correction gives 278.
What this tool does not do / Limits
This uses Cochran's formula for a proportion with simple random sampling. It does not account for clustering, stratification, non-response or design effects, so treat the result as a planning figure and confirm it for your study design.
Frequently asked questions
Why is 0.5 the usual proportion?
It gives the largest sample size, so it is the safe choice when you do not know the true proportion.
What does the population correction do?
For small populations it reduces the required sample, because you are sampling a large share of everyone.
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