Tools›Evals

Sample size for proportions

Estimate sample size for a proportion at a target margin of error.

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Inputs

Change assumptions

Method

n ≈ z²·p·(1−p)/margin².

How to use it

Use the result as a transparent planning estimate. Change one assumption at a time, compare scenarios and move to Toolkit when you need system-level simulation.

Limits

Approximation assumes simple random sampling and independence.

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Local by design

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