Survey Margin of Error Calculator
Enter your sample size and confidence level — and optionally your population size — to see the margin of error your survey results carry.
The formula
e = z × √(p(1−p) ÷ n), multiplied by √((N−n) ÷ (N−1)) when the population size N is known
What the result means
The margin of error describes the range around a reported percentage within which the true value likely falls. If 60% of respondents agree with a statement and your margin of error is ±5%, the true share is likely between 55% and 65% at your chosen confidence level.
Small samples carry wide margins — this is why score swings on a handful of responses usually mean nothing. The finite population correction narrows the margin when your sample is a large share of a known population.