Sample Size Calculator

Answer three questions and find out how many responses you need for results you can trust.

How this works

This uses the standard formula for estimating a proportion with a given confidence level and margin of error, assuming the most conservative case (50/50 split in the underlying population, which requires the largest sample). If you provide a population size, the calculation applies a finite population correction — smaller populations need proportionally fewer responses to reach the same confidence.

Related: how long should a survey be?