AllEasyToolsMathematics
Sample size for a proportion
Sample size for a proportion: calculate from your inputs and inspect the formula. No account required. Processing stays in your browser.
n = ceil(z²p(1−p)/e²)
Normal approximation, large population, independent random sample. Excludes design effects and nonresponse.
How to use this calculator
- Identify the quantities and convert them to the units shown.
- Apply the formula first, then compare with the substitution and result.
- Check the assumptions and whether the order of magnitude makes sense.
Levels are approximate topic groupings, not a complete curriculum for every country. Numerical results are rounded and may lose precision for extreme or nearly singular inputs.
A practical example
Use these sample inputs to check the calculation before entering your own values.
- Expected proportion (0–1)
- 0.5
- Error margin (0–1)
- 0.05
- Critical Z value
- 1.96
Result for this example
- Approximate minimum sample size
- 385