Margin of Error: n = 100, p = 0.5, 95% Confidence
A small survey of just 100 people at 95% confidence with p = 0.5 yields a margin of error of ±9.8%.
How to use this tool
- Enter sample size (n), proportion (p) and z* (confidence level) in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your margin of error and the full breakdown beneath it.
See how a small sample of only 100 respondents results in a large margin of error of nearly 10% at 95% confidence.
Frequently asked questions
- What is the margin of error?
- The margin of error quantifies the uncertainty in a sample proportion estimate. A MOE of ±3% at 95% confidence means the true proportion is within 3 percentage points of the observed proportion 95% of the time.