Sample Size Calculator

How to use the Sample Size Calculator

1. Enter or select: Confidence level, Margin of error, Expected proportion.
2. Fill in what you know of: Population size (optional) — leave the unknown empty.
3. The results (Required sample size, Infinite-population size) are calculated instantly as you type.
4. Use “Copy link” to share the calculation with the same input values.

Formula

• n₀ = z²·p(1−p)/E²
• n = n₀ / (1 + (n₀ − 1)/N)