Margin of error

What each field means

Sample size

Completed surveys.

Population size (optional)

Total universe of people who could answer the survey (e.g., all your customers or all residents of a city). Leave empty if very large or unknown. If provided, the calculation applies the finite population correction, producing a more precise margin of error when the sample represents a meaningful share of the total population.

Confidence level (%)(%)

The probability that the true value for the entire population falls within the calculated margin of error, if you repeated the survey many times with different samples. The most common levels are 90%, 95%, and 99%. A higher confidence level produces a wider margin of error (for the same sample size), since you're demanding more statistical certainty.

Why this metric matters

A 40% ± 8% result can be anywhere from 32% to 48%. Margin decides how conclusive your study is.