Margin of Error Calculator
E = z√(p(1−p)/n) or E = zs/√n depending on mode.
Limitation: Educational survey statistics with z critical values.
How to Use the Margin of Error Calculator
E = z√(p(1−p)/n) or E = zs/√n depending on mode.
Open the Margin of Error calculator and read field labels.
Match the mode
Educational survey statistics with z critical values.
What It Calculates
E = z√(p(1−p)/n) or E = zs/√n depending on mode.
Worked Examples
Poll n=400 p=0.5
Inputs
Result
~±4.9 points.
Mean E
Inputs
Result
zs/√n.
Larger n shrinks E
Inputs
Result
Quarter the MOE vs n=400.
Check your mode
Educational survey statistics with z critical values.
Frequently Asked Questions
Still have questions about this calculation?
Try the CalculatorFormulas
Standard definitions with assumptions noted below.
Formula
Scientific Background
Standard statistics definitions with assumptions stated on-page. Educational only—not professional certification.
Sources & review
Margin of Error Calculator documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.
Last reviewed
July 22, 2026
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