Calculateur de Sample Size
Estimate sample size for a proportion from confidence z-score and margin of error.
Formula and method
This calculator computes Sample size directly in your browser without sending data to an external server.
Mathematical formula
- Sample size:
p>1 ? NaN : z × z × p × (1-p) ÷ e ÷ 100²
Variables and parameters
- Z-score (z): default value 1.96.
- Expected proportion (p): default value 0.5.
- Margin of error (e): default value 5 %.
Some formulas are undefined for certain input combinations (such as division by zero or logarithms of non-positive numbers). In those cases the live tool displays an alert instead of NaN.
Embed this tool
Paste this snippet into your own site or blog post to embed a live, working copy of this tool. It links back to the full page on SpecWhale.
Frequently asked questions
What equation and variables does Sample Size Calculator use?
Sample Size Calculator evaluates outputs such as <strong>Sample size</strong> based on inputs including Z-score, Expected proportion, Margin of error. Check the Mathematical Method section for the explicit formula.
What happens if I enter invalid or zero values into Sample Size Calculator?
If an input combination is mathematically undefined (such as division by zero or negative square roots), SpecWhale alerts you gracefully rather than returning invalid NaN outputs.
Are my calculations in Sample Size Calculator saved or private?
All calculations are 100% private and run locally in your Web browser. Your numbers are never uploaded to any server, but can be saved locally to your device or exported as CSV/JSON.
Is Sample Size Calculator free to use?
Yes. Sample Size Calculator is completely free, has no usage limit, and does not require an account, email, or API key.
Does Sample Size Calculator store or upload my data?
No. Sample Size Calculator calculates everything locally in your browser. Nothing you type is sent to a server or stored by SpecWhale.
How accurate is Sample Size Calculator?
Sample Size Calculator uses a standard formula (see the Method section above for the exact expression). For high-stakes financial, medical, or legal decisions, confirm the result with a professional or an authoritative source before relying on it.
Can I embed Sample Size Calculator on my own website?
Yes. Use the "Embed this tool" snippet on this page to add a free, working copy of Sample Size Calculator to your own blog post or page.