Sample Size Calculator
Enter the confidence level, margin of error and expected proportion — you will get the sample size, i.e. how many people to ask for the survey. If you enter a population, the finite population correction is applied too.
Enter the values — the result shows live here.
How to use
- Choose the confidence level (usually 95%).
- Write the margin of error in percent, for example 5 means ±5%.
- If you do not know the proportion, keep it at 50 — this gives the safest (largest) sample.
- If you know the total population, enter it too.
Note: Formula (Cochran): n₀ = z² x p(1-p) / e², then the population correction n = n₀ / (1 + (n₀ - 1)/N). Sample size is always rounded up (ceil). This is only an estimate; the actual survey design matters too.