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Sample Size for a Proportion

Calculate Sample Size for a Proportion instantly. Free online calculator with the exact formula, a worked example, and metric units. No signup required.

Sample Size for a Proportion

Expected proportion p
Precision E
Z (CI: 1.96=95%)
Sample size n
385
n = z²·p·(1−p) / E²Calculate Sample Size for a Proportion instantly. Free online calculator with the exact formula, a worked example, and metric units. No signup required.

More about: Sample Size for a Proportion

What it calculates

The “Sample Size for a Proportion” calculator computes Sample size n from 3 parameters: expected proportion p, precision e, z (ci: 1.96=95%).

A core calculation for studying, engineering tasks, and checking solutions.

Example calculation

With parameters Expected proportion p = 0.5, Precision E = 0.05, Z (CI: 1.96=95%) = 1.96 the result is 385 (n = z²·p·(1−p) / E²).

How to use

  1. Enter expected proportion p, precision e and z (ci: 1.96=95%) — each field above is adjustable with a slider.
  2. Sample size n is calculated automatically as you type.
  3. Check the worked example below to see the formula applied to real numbers.
  4. Copy the result or bookmark this calculator.

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FAQ

How is Sample Size for a Proportion calculated?
The Sample Size for a Proportion calculator computes Sample size n from expected proportion p, precision e, z (ci: 1.96=95%). Enter your values above and the exact formula is applied instantly; a worked example with real numbers is shown below.
Is the Sample Size for a Proportion calculator free?
Yes. It is completely free, needs no signup, runs entirely in your browser, and sends no data to any server.

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