Sample Size Calculator

All tools

Find how many survey responses you need for a given confidence level and margin of error using Cochran's formula, with an optional finite population correction. Free and instant.

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Use 50% for the most conservative (largest) sample.
Applies a finite population correction when provided.
Required sample size – respondents
With population correction –
Z value used –
Uses Cochran's formula n₀ = z²·p·(1−p) ⁄ e². The finite population correction reduces the figure for smaller populations. The result is rounded up to a whole number of respondents.
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