Sample Size Calculator
Estimate the number of survey responses needed based on confidence level, margin of error, expected proportion and optional population size.
Recommended Minimum Sample0 responses
Initial sample (large population)0
Confidence level95%
Margin of error5%
Expected proportion50%
How to Use the Sample Size Calculator
Enter the confidence level, margin of error and expected proportion or variability to estimate a required sample size.
Practical Example
For a large population, 95% confidence and a 5% margin of error with a 50% expected proportion produces a common estimate near 385 responses.
Factors That Affect the Result
Confidence level, margin of error, population size and expected variability determine the required sample.
Frequently Asked Questions
Why use 50% when the expected proportion is unknown?
It is often conservative because it produces high variability.
Does a smaller margin of error require more responses?
Yes.
Does population size always matter strongly?
For very large populations, the effect becomes relatively small.