Find the plus or minus figure that accompanies any poll or survey result. Enter the sample proportion as a percent, the number of people sampled, and the confidence level, and the tool returns the margin of error and the resulting range around your estimate. The calculation multiplies the z value for your confidence level by the standard error of a proportion, which is the square root of p times one minus p divided by the sample size. Larger samples shrink the margin, while higher confidence widens it. If you have ever seen a poll reported as 52 percent plus or minus 3 points, this is the number behind that phrase. It is essential for reading survey headlines critically and for reporting your own results honestly. All math happens locally in your browser, so nothing you type leaves your device.
It is the plus or minus range around a poll result, showing how far the sample result may sit from the true value.
It multiplies the confidence z-score by the standard error of the sample proportion, which depends on the proportion and the sample size.
More responses reduce the standard error, so the plus or minus range gets tighter as the sample grows.
Find the plus or minus figure that accompanies any poll or survey result. Enter the sample proportion as a percent, the number of people sampled, and the confidence level, and the tool returns the margin of error and the resulting range around your estimate.
Yes. Margin of Error Calculator is completely free, with no sign-up and no usage limits.
Yes. Margin of Error Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Margin of Error Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.