Sample Size Calculator

Calculate required sample size for statistical studies with confidence level, margin of error, and population size.

Sample Size Calculator Features

  • Confidence level selection (90%, 95%, 99%)
  • Margin of error specification
  • Population size input (optional)
  • Step-by-step calculation
  • Mobile-friendly UI

Formula

  • n0 = (ZĀ² Ɨ p Ɨ (1-p)) / EĀ²
  • n = n0 / (1 + (n0-1)/N) (finite population)
  • Z = Z-score for confidence level
  • p = estimated proportion (default 0.5)
  • E = margin of error (as decimal)