Sample Size Calculator
Estimate the sample size needed for a proportion using confidence level, margin of error, expected proportion, and optional finite population size.
Formula without finite population correction:
n₀ = z² · p(1-p) / E²
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Privacy: calculations run locally in your browser. No inputs are stored or transmitted.
How it works
This tool estimates sample size for a proportion. If population size is provided, it also applies finite population correction.
Examples
- 95% confidence, 5% margin, p = 0.5
- Without population correction, this is a common survey planning setup
- Providing population size can reduce the required sample size
When to use this tool
This tool is designed for quick, practical tasks such as everyday calculations, data formatting, or simple conversions. It is best used when you need fast results without installing software or using complex tools.
When to use
- Quick checks or one-time calculations
- Validating or converting data before using it elsewhere
- Simple tasks that do not require advanced software
When not to use
- Critical financial, legal, or medical decisions
- Large-scale or automated processing
- Situations requiring guaranteed precision beyond basic validation
Always review results before using them in important contexts.
About this tool
This tool helps you perform quick utility operations directly in your browser. It runs entirely in your browser without sending data to a server.
You can use this tool when handling simple tasks without installing additional software. The results should be interpreted as a processed output based on your input data.
FAQ
- What does this sample size calculator estimate?
It estimates the sample size needed for a proportion using confidence level, margin of error, and expected proportion.
- What if I do not know the expected proportion?
A common conservative choice is 0.5 because it usually produces the largest required sample size.
- What is finite population correction?
If you provide a population size, the calculator applies a finite population correction to reduce the required sample size when the population is not very large.
- Are calculations stored?
No. Everything runs locally in your browser.