TofuSurveys
Survey Statistics

Margin of Error Calculator

Calculate the margin of error for your survey to understand how accurately your sample represents the entire population.

Calculate Your Margin of Error

Leave blank or enter a large number for infinite/unknown populations

What is Margin of Error?

The margin of error indicates how much your survey results might differ from the true population value. A smaller margin of error means more accurate results.

How to Use This Calculator

  1. 1. Enter your expected sample size (number of responses)
  2. 2. Enter your total population size (or leave large for infinite)
  3. 3. Select your confidence level (95% is standard)
  4. 4. Click calculate to see your margin of error

Quick Tips

  • Larger sample sizes reduce margin of error
  • 95% confidence level is industry standard
  • For most surveys, aim for ±5% or less

Related Tool

Planning a survey? Calculate how many responses you need:

Sample Size Calculator →

Understanding Margin of Error

Why It Matters

If your survey shows 60% support with a ±5% margin of error, the true value is likely between 55% and 65%. This helps you understand the reliability of your findings.

Factors That Affect MOE

  • Sample size: Larger = smaller MOE
  • Confidence level: Higher = larger MOE
  • Population size: Smaller populations = smaller MOE

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