Sample Size Calculator

Baseline, endline and other surveys requiring precise quantitative data need to use a representative sample of respondents. To calculate the required sample size, take advantage of IndiKit’s Sample Size Calculator:

Sample Size Formula

• Confidence Level, tells you how sure you can be of your results. Since it is very rare that relief and development surveys would use anything other than a 95% confidence level, IndiKit’s Sample Size Calculator enters this value automatically.

• Margin of Error (also called confidence interval) is the amount of error that your survey’s findings can tolerate. For example, if your sample uses a 5% margin of error and your survey shows that 63% of women are exclusively breastfeeding, you can be sure that if you had surveyed all breastfeeding women in the given population, the result would be between 58% (63-5) and 68% (63+5). The lower the margin of error you choose, the larger your sample size will be. While the most common margin of error is 5%, surveys focusing on data which are likely to record only small changes (such as prevalence of undernutrition) often only use 2-3%.

• Population Size is the total number of people you are choosing your random sample from. This can, for example, be the total number of your beneficiaries or the number of women living in a given district.

For more information on sampling, read IndiKit’s Rapid Guide to Survey Sampling.