Sample Size Calculator
Math ToolsHow many survey responses do you need?
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All history →Sample Size Calculator — at a glance
Plan a survey with the right number of respondents.
95% confidence
±5% error
Calculate Sample Size
385 responses
How to use it — step by step
Confidence level, margin of error and, if known, the population size.
1
Enter your numbers
Fill in the fields — sensible example values are already filled in.
2
Pick your options
Choose any dropdowns or switches that apply to your case.
3
Calculate Sample Size
Press the button. The result is created instantly on your device.
4
Read the answer
The main answer is shown big at the top, with details below it.
Pro tips
Small things that make the result better.
✦A smaller margin of error needs a much bigger sample.
✦For small populations the needed sample drops a lot.
✦Always plan for some people not replying.
Quick facts
Freeno signup, no limit
Instantresult in a moment
Privatenothing is uploaded
Any devicephone, tablet or PC
Frequently Asked Questions
What is margin of error?+
How far the survey result may differ from the true value, in either direction.
Why 50% by default?+
It is the worst case and gives the largest sample size, so it is safe.
Is my data safe?+
Yes. Everything runs inside your own browser. Your text, files and images are never uploaded to any server.
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