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Calculate Your Polling Margin of Error

Margin of Error (MoE) tells you how far your survey results might be from the true value in the whole population.

For example, if a poll finds that 60% of people support something with a margin of error of ±3%, the true level of support is likely between 57% and 63% (assuming a high‑quality, representative sample).

Margin of Error Calculator (95% CI)

Margin of Error Calculator (95% CI*)

Enter Population, Sample Size, and Incidence Rate to calculate polling Margin of Error (MoE).

Total number of people in the population.
Number of survey respondents.
Percent of population that are eligible to participate.
Formula (worst-case p = 0.5):
Nₑ = N × (IR / 100)
MOE = z · √[ p(1−p)/n ] · √[ (Nₑ − n) / (Nₑ − 1) ]
z = 1.96 for 95% CI. If Nₑ is very large, FPC ≈ 1.

* With a 95% confidence level (the industry standard), you can think of it like this: if you repeated the same survey many times, about 19 out of 20 surveys would give a result within the MoE of the true value, and about 1 out of 20 times (5%) the survey result would be a “fluke”, with the true value falling outside the MoE range.

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