Sample Size Calculator

Please Note:

  • This calculator should be used for simple random samples only.
  • The calculator determines sample sizes for estimates of proportions. In this case Standard Errors are the most appropriate measure of sampling error. Relative Standard Errors are not recommended and can be misleading.
  • We no longer actively support this calculator. Any samples sizes generated are used at your own risk.

Determine Sample Size

Confidence Level:

Population Size:

Proportion:

Confidence Interval:

Upper

Lower

Standard Error

Relative Standard Error

Sample Size:
 
 

How do I use it?

  • Select the Confidence Level you want to work at.
  • If you are sampling from a finite population (one that isn't very large), enter the Population Size.
  • If you already know the estimate Proportion, or want to check the Relative Standard Error of an existing estimate, fill in the Proportion. If left blank it will be assumed to be 0.5.
  • You must fill in one of the Confidence Interval, Standard Error, Relative Standard Error or Sample Size. Make sure the bullet point corresponding to the one you wish to specify is selected.
  • Press Calculate to perform the calculation, or Clear to start again.

Sample Size Calculator Help

Sample Size Calculator Definitions

Sample Size Calculator Examples

Sample Size Calculator Stratification Examples