Sample size, margin of error and significance
Get sample size, margin of error and significance right.
Method & statistics
All tools are free to use, no sign-up required.
Sample size calculator
Work out how many people you need to survey from population size, confidence level and margin of error.
Margin of error calculator
Derive the statistical margin of error from your sample size and result.
Response rate calculator
Work out your response rate and how many invitations you need to hit your target.
p-value calculator
Work out the p-value and significance for two groups — a two-sided z-test for proportions.
Significance calculator
Check whether the difference between two groups holds up statistically — effect size included.
Common questions about the tools
Are the calculators really free?
Yes. Every tool works without a sign-up and without a time limit. The calculation happens entirely in your browser.
Are my inputs stored?
No. Your numbers never leave your browser. They are neither sent to a server nor saved locally — reloading the page resets every calculator.
Which calculator answers which question?
Before you field a survey, the sample size and margin of error calculators help you plan it. Afterwards, NPS, eNPS, CSAT and CES put your results in context, while response rate, p-value and significance support the analysis.
Can I collect these metrics with empirio.ai?
Yes. There are ready-made templates for NPS, eNPS, CSAT and CES. NPS and eNPS are scored automatically in real time; for CSAT and CES you collect the distribution across the steps and work the score out here. Hosted in the EU.