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Sample Size Calculator

Plan sample sizes for proportions, means, two means, and two proportions with upward rounding.

Input

Configure inputs first. Final results, visuals, downloads, and copy summary remain hidden until Calculate Sample Size succeeds.

Sample-size modeConfidence levelPower

Planning proportionMargin of errorPopulation size

Standard deviationMean differenceProportion 1Proportion 2

Nonresponse rate

What This Tool Does

The Sample Size Calculator runs only after you click Calculate Sample Size. It reports unadjusted and nonresponse-adjusted sample-size estimates with visible assumptions.

Method

The calculator applies normal-approximation planning formulas and rounds final required sample size upward.

Worked Example

For p = 0.5, margin of error 0.05, and 95% confidence, the one-proportion estimate is about 385 before nonresponse adjustment.

Common Mistakes

Using p = 0.5 without recognizing it is conservative.
Ignoring nonresponse or dropout.

Limitations

Power approximations are planning estimates.
Complex survey designs and clustering are out of scope.

References

NIST e-Handbook: Quantitative Techniques: NIST/SEMATECH e-Handbook of Statistical Methods, Exploratory Data Analysis quantitative techniques.
RFC 4180: Common Format and MIME Type for Comma-Separated Values (CSV) Files.
Papa Parse Documentation: Papa Parse browser CSV parser documentation.

Why use p = 0.5?

It gives the largest one-proportion sample size when no prior proportion estimate is available.

What is finite population correction?

It reduces the required sample when sampling without replacement from a known finite population.

What is margin of error?

It is the target half-width of the interval estimate under the selected planning method.

Why round upward?

A fractional sample size cannot be collected, and rounding down would undercut the planning target.

Does the Sample Size Calculator calculate automatically while I type?

No. Inputs and CSV previews never produce final statistics until the explicit calculate button is clicked.

Are CSV files uploaded?

No. Selected CSV files are processed locally in the browser. ScholarTool does not upload the file to a third-party calculation or data-analysis API.

Can a p-value prove a hypothesis?

No. A p-value is evaluated against the selected alpha level under stated assumptions; it does not prove the null or alternative hypothesis.

Engineering disclaimer

This statistics tool is intended for education, planning, and preliminary analysis. Review assumptions, study design, and professional statistical judgement before using results in research, engineering, safety, regulatory, or compliance decisions. ScholarTool does not prove hypotheses or replace qualified analysis.

Need Professional Support?

ScholarTool is powered by ScholarEase Consultancy Services LLP. Professional engineering, simulation, research, and technical documentation support is available through the connected services website.

Visit ScholarEase

Last reviewed: 2026-07-07

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Engineering disclaimer

Sample Size Calculator

Input

What This Tool Does

Method

Worked Example

Common Mistakes

Limitations

References

Related Tools

Engineering disclaimer

Need Professional Support?

Sample Size Calculator

Input

What This Tool Does

Method

Worked Example

Common Mistakes

Limitations

References

Related Tools

Engineering disclaimer

Need Professional Support?