Statistics Calculators

Margin of Error Calculator

Calculate the margin of error for a survey result based on sample size, proportion and confidence level.

Margin of error —

About the Margin of Error Calculator

Margin of error describes the range within which the true population value is likely to fall, based on a sample survey result. A smaller margin of error means a more precise estimate.

Formula: MOE = z × √(p(1 − p) ÷ n), using z = 1.645 (90%), 1.96 (95%) or 2.576 (99%)

If you don't know the expected proportion, using 50% gives the most conservative (largest) margin of error. Larger sample sizes shrink the margin of error, which is why pollsters aim for large samples.