Margin Of Error Calculator
Solve MoE = z·√(p(1−p)/n) step by step — free margin of error calculator with worked examples, real-world defaults and instant answers.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Margin of error for a survey proportion — the ±3% headline number.
About Margin Of Error Calculator
The Margin Of Error Calculator solves MoE = z·√(p(1−p)/n) for you with the full working shown — every substitution, every unit, every step, exactly the way a good teacher writes it on the board. A 1 000-person poll carries roughly ±3 points at 95% confidence — and because of the √n, halving the error needs FOUR times the sample.
How to use Margin Of Error Calculator
- 1Enter your known values in the input fields (sensible real-world defaults are pre-filled).
- 2The tool substitutes them into MoE = z·√(p(1−p)/n) and recomputes live.
- 3Read the answer in the result box, then expand the step-by-step solution to see the full working.
- 4Copy the method into your notebook, or change inputs to explore how the result behaves.
Why use Margin Of Error Calculator?
- ✓Solves MoE = z·√(p(1−p)/n) instantly as you type — no submit button, no waiting
- ✓Step-by-step solution shown for every calculation, not just the final answer
- ✓Realistic example values pre-loaded so you can see a worked example immediately
- ✓100% free, no sign-up, runs entirely in your browser — your numbers never leave your device
- ✓Mobile-friendly and fast enough to use mid-homework or mid-lesson
Frequently asked questions
What formula does the Margin Of Error Calculator use?+
It uses MoE = z·√(p(1−p)/n). The steps section shows the formula with your actual numbers substituted, so you can follow (and verify) every stage of the calculation rather than trusting a black box.
What should I keep in mind when using this calculator?+
A 1 000-person poll carries roughly ±3 points at 95% confidence — and because of the √n, halving the error needs FOUR times the sample. p(1−p) peaks at p = 0.5, so pollsters use 0.5 for worst-case planning.
Is the Margin Of Error Calculator free to use?+
Completely free, with no sign-up or limits. All computation happens client-side in your browser, so it is fast, private, and works even on slow connections once the page has loaded.
Can I use this for homework, teaching or exam prep?+
That is exactly what it is built for. The step-by-step working mirrors how solutions are presented in class, so you can check homework, build worked examples for teaching, or practise method recall before exams.
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Want Margin Of Error Calculatoron your own site? Paste this snippet into any HTML page — it's free, with no API key or sign-up. The tool loads in an iframe and keeps working exactly as it does here.
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