Margin of error calculator
How precise is a result from the number of interviews you have?
Plus or minus 4.4 points
This is the margin of error for a result near the share you entered, at the confidence level you chose.
How to read it
Enter the number of completed interviews and the share you saw. The calculator returns the plus or minus range at your chosen confidence level. If the sample is weighted or comes from a panel, raise the design effect so the range holds up.
To plan a sample before fieldwork, use the sample size calculator. To see how we report panel results, read our standards.
Frequently asked questions
What is a margin of error?
It is the range around a survey result that random sampling alone would produce, at the confidence level you choose. It says nothing about who was missed or how questions were worded.
Is the margin of error the same for every question?
No. It is widest for results near the middle and narrower near the extremes. The calculator uses the share you enter.
Why does the design effect matter?
Weighting makes a result less precise than a simple random sample of the same size. A larger design effect gives a wider, more honest range.
How should I report precision for a weighted panel sample?
Report a credibility interval with the design effect applied, and state the method alongside it: who was asked, how, when and how the results were weighted.