Sample Size Calculator

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Estimates the minimum sample size required to achieve a desired level of confidence and margin of error for a study.

How To Use

How to use this calculator

Start with your values, or try a preset.

Step 1

Enter Population Size, Confidence Level, Margin of Error, and Response Distribution in the units shown.

Step 2

Read Z-score, p, q, Sample Size, and Rounded Sample Size in the results panel. Results update as you change the inputs.

Step 3

Choose a preset to load an example, then adjust the values for your situation.

Worked Examples

See the inputs and their calculated results.

Population Size: 10,000 People; Confidence Level: 99 %; Margin of Error: 2 %; Response Distribution: 50 %

Z-score: 2.58; p: 0.5; q: 0.5; Sample Size: 2,937.97779; Rounded Sample Size: 2,938

Population Size: 1,000 People; Confidence Level: 95 %; Margin of Error: 5 %; Response Distribution: 50 %

Z-score: 1.96; p: 0.5; q: 0.5; Sample Size: 277.5401688; Rounded Sample Size: 278

Population Size: 500 People; Confidence Level: 80 %; Margin of Error: 10 %; Response Distribution: 50 %

Z-score: 1.28; p: 0.5; q: 0.5; Sample Size: 37.85862171; Rounded Sample Size: 38

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Use calculators for algebra, geometry, trigonometry, probability, statistics, averages, z-scores, tests, and graphing tasks.

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