Survey sample size calculator
How many people need to answer your survey before you can trust the result? Pick a confidence level and margin of error and find out.
Survey setup
Defaults — 95% confidence, ±5% margin — fit most surveys.
How sure you want to be that the sample reflects the population.
The ± range around each result. Smaller margin → bigger sample.
Total people in the group you're surveying. Leave empty if very large or unknown.
Saved on this device. Your numbers never leave your browser.
Recommended sample
Responses needed
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Assumes the most conservative case — a 50/50 answer split (p = 0.5).
This is completed responses. Divide by your expected response rate to know how many people to invite.