Free Survey Calculators
A set of free, instant calculators for the numbers that come up most when you plan, run, and analyze a survey. Everything runs in your browser — nothing is uploaded, and you don't need an account. Each tool also explains the formula behind it so you can trust and reproduce the result.
Sample Size Calculator
Find how many responses you need for a given confidence level and margin of error, with an optional finite-population correction.
Open calculatorNPS Calculator
Calculate NPS from promoter/passive/detractor counts, or paste a column of 0–10 ratings to score them automatically.
Open calculatorSurvey Response Rate Calculator
Calculate your response rate from responses and invitations, then plan how many invites you need to reach a response target.
Open calculatorCSAT Calculator
Calculate CSAT as the percentage of satisfied (top-box) responses out of your total responses.
Open calculatorWhy we built these
Good survey decisions rest on a few standard calculations — how many responses you need, how loyal your customers are, how well your distribution is performing. Reaching for a spreadsheet every time is slow and error-prone, so we turned the formulas our own product uses into free tools anyone can use, whether or not they build their survey with SurveyExtreme.