Sample size for a proportion
Enter the expected proportion, margin and confidence level.
Result
For 95% confidence, 0.5 proportion and 5% margin, n ≈ 385.
Example
Find the sample size needed for a proportion estimate.
For 95% confidence, 0.5 proportion and 5% margin, n ≈ 385.
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Methodology
n = z² × p × (1 − p) / margin² for the chosen confidence level.
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