Margin of Error Calculator
Calculate the margin of error for surveys and polls.
Formula
ME = z × √(p × (1 − p) / n)
| Parameters | Result |
|---|---|
| n=100, p=0.5, 95% | ± 9.80% |
| n=400, p=0.5, 95% | ± 4.90% |
| n=1000, p=0.5, 95% | ± 3.10% |
| n=1000, p=0.5, 99% | ± 4.07% |
About
The margin of error tells you how much survey results may differ from the true population value. A smaller margin means more precise results.
Increasing sample size reduces the margin of error. A proportion of 0.5 gives the maximum (most conservative) margin of error.