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Sample Size Calculator

How many people need to complete your survey to reach valid data?

What margin of error can you accept?

5% is a common choice.


The margin of error refers to the degree to which the researcher believes the data may not represent the whole population. A lower margin of error requires a larger sample size.

What is your desired confidence level?

Typical choices are 90%, 95%, or 99%.


The confidence level refers to the confidence the researcher has that the data truly represents the whole population. A higher confidence level requires a larger sample size.

What is the population size?

If you don't know, use 20000.

The population size refers to how many people there are to choose from for your random sample. The sample size doesn’t change much for populations larger than 20,000.

What is the response distribution?

The most conservative choice is 50%.


Response distribution refers to how you expect people to respond to the survey questions. If sample data is skewed highly to one end, the population probably is too. If you don’t know, use 50%. This gives you the largest sample size.

Your recommended sample size is:


This is the minimum recommended number of complete responses to every question on your survey to obtain valid data within the tolerances you specified.