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Sample size calculator

How many respondents do you actually need?

A statistical calculation, not a hunch. Enter your population, the margin of error you accept and the confidence level you want: the tool returns the number of respondents you need.

Opens in a new tab, on its own domain.

What it is for

Too few respondents and the result cannot be defended; too many and you pay for nothing. This calculator settles it with the standard survey formula and shows what each parameter does to the answer.

Who it is for

Anyone preparing a study, a survey or a user test who has to justify their sample: research managers, marketers, product managers, students.

How it works

  1. 1

    Enter your population size, or leave it undetermined if you do not know it.

  2. 2

    Pick your margin of error and your confidence level.

  3. 3

    Read the required sample size, then move the parameters to trade cost against precision.

The other free tools

And when you want real answers?

These tools clear the ground. Panelia surveys hundreds of synthetic respondents and hands you a calibrated purchase-intent distribution, confidence intervals included.