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Minimum Sample Size for Survey Accuracy Calculator

n = z²·p(1−p)/E² — sample size for a given margin of error.

Calculates the minimum sample size needed for a survey or proportion estimate at a specified confidence level and margin of error.

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

n = (z* × σ / E)² or n = z²×p(1−p)/E² for proportions

In depth

Calculates the minimum sample size needed for a survey or proportion estimate at a specified confidence level and margin of error.