Overview
What this tool does
Sample Size Calculator: Estimate a survey sample size from confidence, margin of error, expected proportion and optional finite population. Explicit workflow boundaries Visible limitations and recovery Release-gated evidence
- Prepare 95% confidence, 5% margin and a 50% expected proportion.
- Local statistical formula engine with distribution quantiles.
- Confirm that the large-population estimate rounds up to 385 responses, then review the stated limits before copying or downloading anything.
Method
How this tool works
Local statistical formula engine with distribution quantiles. The calculation or transformation is deterministic for the same supported input, and the worked example below shows the intended scope.
Example
Sample Size Calculator worked example
Input: 95% confidence, 5% margin and a 50% expected proportion.
Expected output: the large-population estimate rounds up to 385 responses.
Limits
Assumptions and limits
- Inputs and files stay in this browser and are excluded from analytics.
- The worked example assumes 95% confidence, 5% margin and a 50% expected proportion.
- Units, dates, rates, selections and source-file quality are taken exactly as entered unless the workspace labels a default.
- Sample Size Calculator implements the stated bounded method, not every possible interpretation of the task.
- Check important output against the original data or an independent method before relying on it.
Privacy
Local processing
Values and files are processed locally in this browser unless the workspace explicitly identifies an optional network feature. Great Future does not intentionally collect tool inputs.
Sources
Method references and scope
Internal review owner: Great Future Product Engineering.
- Sample Size Calculator method specification — Great Future Product Engineering. Reviewed 2026-08-29. Internal implementation reference documenting the formula, data assumptions or deterministic transformation used by this tool; it is not an external authority.
Questions
Frequently asked questions
What input should I prepare for Sample Size Calculator?
Prepare 95% confidence, 5% margin and a 50% expected proportion. Keep the original values or file available so you can compare the result.
What should I verify after using Sample Size Calculator?
Verify that the large-population estimate rounds up to 385 responses. Sample Size Calculator implements the stated bounded method, not every possible interpretation of the task.
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