Raosoft Sample Size Calculator

The Raosoft Sample Size Calculator is a statistical tool that helps determine the appropriate number of respondents needed for a survey or research study. It’s based on established statistical formulas and takes into account your population size, desired confidence level, and acceptable margin of error to provide an accurate sample size recommendation.

Our calculator uses the standard sample size formula employed by professional researchers and statisticians. The accuracy depends on the parameters you provide, especially the population size. For very large populations (over 100,000), the population size becomes less significant in the calculation.

The most commonly used confidence level is 95%, which means if you were to conduct the same survey 100 times, the results would be within your margin of error 95 times. Higher confidence levels (99%) require larger sample sizes but provide more certainty. For most general research, 95% is sufficient.

A 50% response distribution represents maximum variability in responses, which yields the largest possible sample size. This conservative approach ensures your sample will be adequate regardless of how responses are distributed. If you know the expected distribution will be different (e.g., 70/30), you can adjust this parameter for a more precise sample size.

Yes, our calculator automatically applies a finite population correction for populations under 100,000. This adjustment prevents overestimation of required sample sizes for smaller populations where sampling a large percentage of the population would be impractical or unnecessary.