This sample size reference table shows the required sample size for a range of margin of error values, assuming a proportion of 0.5 and a confidence level of 95% (z = 1.96). Every figure is computed with the same engine that powers our Sample Size Calculator, so the numbers are exact.
| Margin of error | Required sample size |
|---|---|
| 1.3% | 5,683 |
| 2.5% | 1,537 |
| 3.8% | 666 |
| 5% | 385 |
| 7.5% | 171 |
| 1% | 97 |
| 15% | 43 |
| 25% | 16 |
| 35% | 8 |
| 5% | 4 |
How to use this table
Find the row closest to your margin of error and read across to the required sample size. For a value between two rows, the real figure sits between them — or enter your exact numbers in the Sample Size Calculator for a precise answer.
Need a value that is not in the table? — the Sample Size Calculator does it instantly, for free, with the formula and a worked example built in.
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