Sample Size Calculator | Free Online Tool

What is the proportional survey sample size calculator?

Based on the confidence level, allowable error, estimated proportion and limited matrix correction, estimate the number of samples required for the proportional survey. ToolHub places the core computing entirely within the browser, allowing immediate use on both desktop and mobile devices, without the need to register an account or send content to the backend.

How to use this tool?

Enter the data according to the field prompts and select the required processing method.
Click "Process Now" to view the results, indicator summary and necessary error messages.
After confirming that the content meets actual needs, you can copy the results or download them into files for further use.

Suitable use cases

Questionnaire planning, poll sampling and quality spot check design. All processing is completed in the current page, which is especially suitable for workflows that do not want to post internal data to remote services.

Interpretation of results and precautions

This formula assumes simple random sampling, and a stratified or clustered design requires the inclusion of design effects. Tools will validate basic input formats and provide readable error messages, but production environments should still be reconfirmed against source specifications, business rules, or professional requirements.

Browser and device support

Sample Size Calculator supports current Chrome, Edge, Firefox, and Safari releases. Mobile and desktop layouts use the same validation rules documented on this page.

Frequently Asked Questions

Will the proportional survey sample size calculator upload data to the server?

No. Tool functions are executed directly within the current browser tab, and input and generated results will not be uploaded or saved by ToolHub.

In which use cases is the proportional survey sample size calculator suitable?

Questionnaire planning, poll sampling and quality spot check design

Do I need to install software before using the proportional survey sample size calculator?

No need. Use a desktop or mobile browser that supports modern JavaScript, and no account is required.

What are the limitations of this tool?

This formula assumes simple random sampling, and a stratified or clustered design requires the inclusion of design effects.

Is manual inspection required after the results are generated?

Needed. Tools can assist with calculations, conversions, or formatting, but before going online, importing data, or making business decisions, the results should still be reviewed according to actual specifications.

Sample Size Calculator: inputs, output, and reproducible example

Use the free Sample Size Calculator online. Fast, private, mobile-friendly, and processed directly in your browser.

What this page actually processes

Field	Control	Default example	Validation role
confidence level	Selection	`95%`	confidence level is read by the browser as a selection value before the tool runs.
Allowable error %	Number	`5`	Allowable error % is read by the browser as a number value before the tool runs.
Estimated proportion %	Number	`50`	Estimated proportion % is read by the browser as a number value before the tool runs.
Number of parent bodies (0 means no limit)	Number	`0`	Number of parent bodies (0 means no limit) is read by the browser as a number value before the tool runs.

Reproduce the built-in example

Start with confidence level = 95%; Allowable error % = 5; Estimated proportion % = 50; Number of parent bodies (0 means no limit) = 0, then run Sample Size Calculator. Change one input at a time so the effect on the result remains traceable.

After validating confidence level, allowable error %, estimated proportion %, number of parent bodies (0 means no limit), the page displays its result in the output workspace and enables the relevant copy or download action.

When to use it and how to interpret the result

Limits and checks before use

Page verification record

Controls inspected4 documented inputsResult pathValidate → process → review → copy/downloadLast content review2026-09-02