Sampling Calculator
Calculate the sample size you need for surveys, evaluations, and monitoring activities
More Options
Result
Example, change any input412
respondents
Margin of Error Comparison
| Margin of Error | Sample Size |
|---|---|
| 4% | 630 |
| 5% (selected) | 412 |
| 6% | 289 |
How It Works
- Set Your ParametersPopulation, confidence and margin of error. Add a design effect for cluster sampling.
- See the MathCochran's formula with a finite population correction, then design effect and non-response.
- Keep ItDownload it as Word, save it to MeStudio, or share a link to the same numbers.
How the Calculation Works
This calculator uses Cochran's formula for sample size determination, which is the standard approach for survey research:
n₀ = (Z² × p × (1-p)) / e²
Where Z is the z-score for your confidence level (1.96 for 95%), p is the expected proportion, and e is the margin of error. For finite populations, a correction factor is applied:
n = n₀ / (1 + (n₀ - 1) / N)
The final sample is then adjusted for design effect (DEFF) when using cluster or stratified sampling, and for expected non-response:
n_final = (n × DEFF) / (1 - non-response rate)
Need Help with Your Sampling Strategy? We help M&E teams design samples that balance rigor with what the budget allows. See services or talk to us.