What is the Margin of Error Calculator?
Calculate the margin of error for a survey or poll. Paste a list of numbers from any spreadsheet or document and get descriptive statistics instantly. Each statistics calculator also charts your data so outliers stand out.
How to use the Margin of Error Calculator
- Enter your sample size, your confidence level, your observed proportion.
- Results update automatically as you type; you can also press Calculate.
- Read the output: margin of error, confidence interval.
- Use the 📊 chart to see the result visually, then copy or share it.
Formula and method
Worked example
With sample size = 1,000, confidence level = 95%, observed proportion = 50 %, the Margin of Error Calculator returns margin of error: ±3.10%; confidence interval: 46.90% – 53.10%.
Tips for better results
- Use sample standard deviation (n − 1) for samples and population (n) for complete data sets.
- Check the chart for outliers before trusting a mean.
- Quartiles here use the inclusive interpolation method, matching Excel’s QUARTILE.INC.
Frequently asked questions
What does the Margin of Error Calculator do?
Calculate the margin of error for a survey or poll.
How is it calculated?
The Margin of Error Calculator uses this method: MOE = z × √(p(1 − p) ÷ n).
Can you show an example?
With sample size = 1,000, confidence level = 95%, observed proportion = 50 %, the Margin of Error Calculator returns margin of error: ±3.10%; confidence interval: 46.90% – 53.10%.
Is the Margin of Error Calculator accurate?
Yes. It uses standard formulas and exact constants, and the results are verified by our automated test suite. Values are displayed to up to 12 significant digits.
Is this tool free and private?
Yes — the Margin of Error Calculator is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.
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