Margin of Error Calculator

Find the ± margin of error for a poll or survey result.

Fractions and decimals both work.
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Margin of error
Likely range
Critical value (z)
Finite population correction
Work

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How to Calculate Margin of Error

MOE = z × √(p(1 − p) ÷ n) × √((N − n) ÷ (N − 1))

The last factor, the finite population correction, only matters when the sample is a big share of the population.

Worked Example

Tips

Margin of error covers random sampling error only, not biased questions or who chose to respond. The difference between two candidates has a larger margin than either number alone.