Sample Size Calculator

Calculate required sample size for surveys and studies with confidence levels and margin of error.

Calculator

Range: 0.1% to 50%

If blank, uses conservative estimate of 50%

If provided, applies finite population correction

Enter the confidence level, margin of error, and other parameters to calculate the required sample size.

Complete User Guide

Calculation Types

  • Proportion: For surveys estimating proportions or percentages (e.g., approval rating, preference)
  • Mean: For studies estimating means or averages (e.g., average income, test scores)

Key Parameters

  • Confidence Level: Probability that the true value lies within the margin of error (typically 95%)
  • Margin of Error: Maximum expected difference between sample and population (e.g., ±5%)
  • Population Proportion: Expected proportion (if known, otherwise uses 50% for conservative estimate)
  • Standard Deviation: Required for mean calculations
  • Population Size: If provided, applies finite population correction

Examples

Example 1: Survey Proportion

Input: 95% confidence, 5% margin of error

Result: Sample size ≈ 385

Example 2: Mean Calculation

Input: 95% confidence, margin of error = 2, standard deviation = 10

Result: Sample size ≈ 97

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