Sample Size Calculator

Respondents needed for your margin of error.

Input Parameters

Margin of error (±)

Std. deviation (σ)

Confidence level

Calculation Summary

Required sample size97people

z-value1.96

(zσ/E)²96.04

175 available

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About this calculator

Sample size from margin of error, standard deviation and confidence level via n = (zσ/E)².

Halve the margin?

Quadruple the sample — size scales with the square of precision.

Unknown σ?

Pilot data or range/4 estimates work; conservative 0.5 suits proportions.

Rounded up?

Always round up: 96.2 people means surveying 97.