Calculate the number of respondents needed for a survey.
Survey Parameters
50%
Requirement Summary
Recommended Sample Size385respondents
Z-Score1.96
Sample Size vs Margin of Error
About this calculator
Overview
To get a statistically valid result from a survey or study, you don't need to ask everyone—just enough people to accurately represent the group. This calculator helps determine that minimal number based on your desired confidence and accuracy.
💡
Pro Tips
Use 50% for population proportion if you are unsure; it yields the largest, most conservative sample size.
As your population size (N) grows very large, the required sample size (n) stays almost constant.
A margin of error of 5% is standard for many professional surveys.
!
Fun Facts
"Increasing sample size has diminishing returns. To cut your margin of error in half, you generally need four times as many participants!"
"The US census used to sample everyone, but now uses statistical sampling for many detailed metrics to save billions of dollars."
"Most national political polls in the US use a sample size of around 1,000 people to represent 330+ million citizens."
Formula: n = [z² * p * (1-p) / e²] / [1 + (z² * p * (1-p) / e²N)]
