Free online sample size calculator for research and surveys. Calculate the required sample size for mean estimation or proportion estimation. Choose confidence level, margin of error, and population characteristics. Instant results, pure client-side.
A clean, fast sample size calculator for researchers, students, and survey designers. Calculate the minimum sample size needed to estimate a population mean or proportion with a specified confidence level and margin of error. Supports finite population correction for small populations. All calculations happen instantly in your browser — no server, no delay, no data sent anywhere.
Yes, completely free. No registration, no ads, no limits.
Use mean estimation when you want to estimate an average value (like average age, weight, or score). Use proportion estimation when you want to estimate a percentage or rate (like election polling or product satisfaction).
If unknown, you can estimate it from a pilot study, use a rule of thumb for your field, or run a small preliminary survey. For proportions, if unsure, use 0.5 which gives the most conservative (largest) sample size.
Use it when your population is small and known (e.g., a company with 500 employees). For large or unknown populations (e.g., all consumers in a country), leave the population field blank.
Absolutely. All calculations happen inside your browser. Nothing is sent to any server.