Margin of error calculator

With the sample already collected, the margin of error tells you how precisely each percentage can be read. A result of 42% with ±4.9 points means the universe’s true value lies, at the chosen confidence level, between 37.1% and 46.9%.

This number also decides whether a difference is real. If two readings give 42% and 44% and the margin is ±4.9, you cannot claim it went up: the intervals overlap almost entirely.