Sample Size Calculator for Means

Plan the number of observations you need to estimate a population mean with the desired precision. Enter your expected standard deviation, confidence level, and the margin of error you want to achieve to get an immediate sample size recommendation.

When to choose the mean option

• Designing a study around a continuous outcome such as height, reaction time, or cost
• Wanting to keep the confidence interval for the mean within a specified width
• Adjusting for finite population size while keeping a clear margin target

Key inputs

• Confidence level (e.g., 95%)
• Expected standard deviation
• Target margin of error for the mean
• Optional population size for finite population correction