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Survey Sample Size Calculator

Estimate sample size for a population proportion.

Tool inputs stay in your browser · optional AI search sends your query

Good to know: Large-population normal approximation n=z²p(1−p)/e², rounded up. Assumes simple random sampling. Does not include design effects, finite-population correction or non-response.

How to use it (step by step)

  1. 1Fill in the boxes: “Margin of error (%)”, “Expected proportion (%)”, “Confidence”. Example numbers are already there so you can see how it works; replace them with yours.
  2. 2The result updates instantly as you type (on a phone it is below the boxes).
  3. 3The bold line is the main answer. Tap Copy next to any value to copy it.

Words to know

Percentage
A part out of 100. 25% of 200 = 50.
Random
Chosen by chance so every option has an equal, unpredictable chance of being picked.

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