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Sample Size Calculator

Determine the right sample size for your survey. Based on the Cochran formula with a finite population correction, this calculator tells you how many responses you need for a given confidence level and margin of error.

Population size

Confidence level

90%95%99%

Margin of error (%)

Expected proportion (%)

Uses the Cochran formula n₀ = z²·p(1−p)/e² and the finite population correction n = n₀/(1+(n₀−1)/N). Leave population size empty for infinite populations.