Poll margin of error calculator
Every sample poll carries a margin of error that depends on the sample size, not the population size. The tool estimates it and checks whether the gap between two percentages clears the margin.
The margin covers sampling error only. It does not cover non-response, question wording, option order or the systematic refusal of one group of voters — sources of error that in practice often exceed the calculated margin.
Frequently asked questions
Why does population size not matter?
Because the formula depends on the square root of the sample. A sample of 1,000 gives the same margin in a city of 100,000 and in a country of 19 million.
What does ±3% mean?
That in 95 out of 100 identical polls, the true value would fall between 29% and 35% for a 32% result. It does not mean the result is certainly in that range.
Why does the gap between candidates have a bigger margin?
Because there are two estimates with error, and the errors compound. The gap carries roughly twice the individual margin.