Free survey & statistics calculators
Six calculators for planning and analysing research — sample size, margin of error, NPS, CSAT, A/B significance and p-values. No sign-up, no email, no limits.
Sample Size Calculator
Work out how many survey responses you need for results you can trust, at any confidence level and margin of error.
Open calculatorNPS Calculator
Turn promoter, passive and detractor counts into a Net Promoter Score, with the breakdown behind the number.
Open calculatorCSAT Calculator
Calculate a customer satisfaction score from 1-5 ratings, using the standard top-two-box method.
Open calculatorMargin of Error Calculator
See how precise your survey results really are, given the sample you actually collected.
Open calculatorA/B Testing Significance Calculator
Check whether the difference between two variants is real or just noise, with p-value, confidence interval and power.
Open calculatorP-Value Calculator
Convert a z, t or chi-square statistic into a p-value for one- or two-tailed tests.
Open calculatorWhich one do you need?
Before you send a survey, use the sample size calculator to work out how many completed responses you need. Divide that by your expected response rate to size the send itself.
After responses come in, the margin of error calculator tells you how precise your results actually are. It's the exact inverse of the sample size calculator, so the two always agree.
To score customer feedback, use the NPS calculator for relationship-level loyalty and the CSAT calculator for satisfaction with a specific interaction.
To compare two options, the A/B significance calculator tells you whether a difference is real. For a test statistic you already have, the p-value calculator converts z, t or chi-square into a p-value.
Frequently asked questions
Are these calculators free to use?
Yes, completely. Every calculator runs in your browser with no sign-up, no email gate, and no limit on how often you use them. Nothing you enter is sent to a server.
How accurate are the results?
The calculators use real statistical distribution functions rather than rounded lookup tables, so results are accurate to far more decimal places than we display and work at any confidence level, not just the common ones. Every formula is covered by automated tests against published critical values.
Can I share or save a calculation?
Yes. Every calculator has a "copy link" button that produces a URL containing your exact inputs. Anyone who opens it sees the same numbers and the same result — useful for sharing working with a colleague.
Which calculator should I start with?
If you are planning a survey, start with the sample size calculator to work out how many responses you need. If you have already collected responses, start with the margin of error calculator to see how precise your results are.
Run the survey, not the spreadsheet
SurveyKar calculates NPS, CSAT and response rates automatically as answers arrive — live scores, trends and segment breakdowns without exporting anything.