Sample Size Calculator

Please Note: This calculator should be used for simple random samples only

Determine Sample Size

Confidence Level:

Population Size:


Confidence Interval:



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.