Margin of Error Calculator
Calculate margin of error for survey results.
Margin of Error Calculator
Calculate the margin of error for your survey results to understand the precision of your data.
Formula: MOE = Z × √((p × (1-p)) ÷ n)
Survey Parameters
Enter your survey details to calculate margin of error.
Number of survey responses collected
Total people you could have surveyed
% who answered a certain way (50% is most conservative)
Margin of Error
The accuracy of your survey results.
±4.9%
Good Precision
Confidence Interval
Range where the true value likely falls.
Lower Bound
45.1%
Observed Value
50%
Upper Bound
54.9%
At 95% confidence, the true value is between 45.1% and 54.9%
Calculation Details
With and without finite population correction.
Standard MOE
±4.99%
without FPC
Adjusted MOE
±4.90%
with FPC
Understanding Margin of Error
Margin of error indicates how much survey results may differ from the true population value.
Key Factors
- Sample size — Larger samples = smaller MOE
- Confidence level — Higher confidence = larger MOE
- Population size — Matters more for small populations
- Response proportion — 50% gives the widest (most conservative) MOE
MOE Guidelines
- ±3% or less — High precision, reliable for decisions
- ±5% — Standard precision, commonly accepted
- ±10% — Directional only, use with caution