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Proportion Sample Size Calculator

Estimate a sample size for a specified absolute proportion margin.

Data stays on this deviceConvention explained below

Data and assumptions

Runs on your device

STATISTICAL RESULT

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter planning proportion, margin in percentage points, critical z value.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

n = ceil[z²p(1 − p)/(margin/100)²].

A WORKED EXAMPLE

Using planning proportion = 0.5, margin in percentage points = 5, critical z value = 1.95996398454, the result is 385 observations. Change these example inputs to match your task; use the method above to check each step.

What to keep in mind

Simple random sampling approximation without finite-population adjustment or nonresponse inflation. A descriptive or probability calculation under the stated assumptions. Check the sample design and model before interpreting results.

Common questions

Which inputs does this calculation need?

Estimate a sample size for a specified absolute proportion margin. Enter planning proportion, margin in percentage points, critical z value. The filled example is editable and is not a saved personal record.

How should I interpret the result?

Simple random sampling approximation without finite-population adjustment or nonresponse inflation. A descriptive or probability calculation under the stated assumptions. Check the sample design and model before interpreting results.

Methodology maintained by ClarityKit. How these tools are built and checked.