Margin of Error Calculator
The ± figure behind any poll or survey result.
Enter your values
ⓘ Live results
Results
- Margin of error
- ± 3.1 percentage points
- Confidence interval
- 48.9% to 55.1%
- Is a 50% result inside the interval?
- Yes — result is a statistical tie
Quick answer
Margin of error is z × √(p(1−p)/n) — the range within which the true population value likely falls.
MOE = z·√(p(1−p) ÷ n)
How to use the Margin of Error Calculator
- 1Enter your sample size.
- 2Enter the percentage you observed.
- 3Pick the confidence level.
Worked example
Using the values the calculator loads with:
Inputs
- Sample size1000
- Observed percentage52 %
- Confidence level95%
Results
- Margin of error± 3.1 percentage points
- Confidence interval48.9% to 55.1%
- Is a 50% result inside the interval?Yes — result is a statistical tie
Frequently asked questions
Why do polls say ±3?
That is the margin at 95% confidence for a sample of about 1,067 — the industry's standard cost-accuracy compromise.
Does margin of error cover bias?
No. It only measures sampling randomness. Non-response and bad question wording add error it cannot detect.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.