Sample Size Calculator
Find the minimum sample size for your survey or study.
Sample Size — Formula
For proportions (infinite population)
n = (z* ² × p × (1−p)) / e²
Where e = margin of error (as decimal), p = expected proportion (default 0.5).
Finite population correction
n₁ = n₀ / (1 + (n₀−1) / N) — reduces sample size when population is small.
