How it works
Margin of error in percentage points = z × √(p(1−p)/n) × 100.
Input definitions
- Observed proportion (%)
- Enter the value in the labeled unit.
- Sample size
- Enter the value in the labeled unit.
- Confidence z value
- Enter the value in the labeled unit.
A worked example
- Observed proportion (%)
- 50
- Sample size
- 1000
- Confidence z value
- 1.96
Assumptions & limits
Uses only the values entered. Rates are illustrative inputs, not live quotes, legal rules or personalised advice. Check provider terms, local requirements and measurements before acting.
Sources & review
Maintained by AnsRio. Methods and examples use automated checks; this does not imply independent professional certification.
Method updated 2026-10-19. Content checked against the stated method and examples. Our verification approach.
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Common questions
Does this include survey design effects?
No. Weighting, clustering, nonresponse and finite populations can change uncertainty.
How does Proportion margin of error calculate the result?
Margin of error in percentage points = z × √(p(1−p)/n) × 100.
What should I verify before using Proportion margin of error?
Uses only the values entered. Rates are illustrative inputs, not live quotes, legal rules or personalised advice. Check provider terms, local requirements and measurements before acting.