Sample Size Calculator
Free sample size calculator — step-by-step solution, worked examples, instant answers.
Sample size for a survey — solve the MoE formula backwards.
About Sample Size Calculator
The Sample Size Calculator solves n = z²·p(1−p)/e² (then finite-population correction) for you with the full working shown — every substitution, every unit, every step, exactly the way a good teacher writes it on the board. Counter-intuitive but true: the required sample barely depends on population size — ±5% needs ~385 people whether the city has 20 thousand or 20 million (the correction only matters when you'd sample more than ~5% of ev…
How to use Sample Size Calculator
- 1Enter your known values in the input fields (sensible real-world defaults are pre-filled).
- 2The tool substitutes them into n = z²·p(1−p)/e² (then finite-population correction) 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 Sample Size Calculator?
- ✓Solves n = z²·p(1−p)/e² (then finite-population correction) 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 Sample Size Calculator use?+
It uses n = z²·p(1−p)/e² (then finite-population correction). 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?+
Counter-intuitive but true: the required sample barely depends on population size — ±5% needs ~385 people whether the city has 20 thousand or 20 million (the correction only matters when you'd sample more than ~5% of everyone). Budget for non-response: a 50% response rate means inviting twice the computed n.
Is the Sample Size 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.
Embed Sample Size Calculator on your website
Want Sample Size 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.
<iframe src="https://tooljolt.com/tools/sample-size-calculator" width="100%" height="640" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" title="Sample Size Calculator — ToolJolt" loading="lazy"></iframe>Related Science tools
Centripetal Force Calculator
Solve F_c = m·v² / r step by step — free centripetal force calculator with worked examples, real-world defaults and instant answers.
● LiveForce Calculator
Solve F = m · a step by step — free force calculator with worked examples, real-world defaults and instant answers.
● LiveFree Fall Calculator
Solve h = ½gt² , v = gt step by step — free free fall calculator with worked examples, real-world defaults and instant answers.
● Live