Overview
What Is a Sample Size Calculator?
This tool calculates the minimum sample size needed for a survey or study to achieve a desired confidence level and margin of error.
Calculate the required sample size for a survey.
This tool calculates the minimum sample size needed for a survey or study to achieve a desired confidence level and margin of error.
Useful for planning surveys, studies, or polls that need statistically valid results.
Input the total population you're studying (or a large number if unknown).
Input your desired statistical parameters.
The result updates automatically.
The probability that your sample accurately represents the true population value - 95% is commonly used.
The range within which the true population value likely falls, based on your sample - smaller margins require larger samples.
Less than you might expect - beyond a certain population size, required sample size plateaus rather than scaling proportionally.
5% is common for general surveys, though more precise research may use smaller margins like 3% or less.
95% is the most commonly used standard in social science and market research.
No, calculations happen entirely in your browser.
Higher confidence and lower margin of error improve statistical reliability, but require larger, more resource-intensive samples.
Sample size planning principles are related, though A/B testing often uses specialized calculations for statistical power.
It's a good target, though practical research often rounds up or adjusts for expected response rates.
Yes, completely free with no sign-up required.