How to use this calculator
- Enter values from one consistent scope and period.
- Check that each field uses the unit shown beside it.
- Select Calculate to update the result.
- Review the secondary metrics and interpretation before comparing scenarios.
#2023 · Legal & Compliance Tool
Vendor Compliance Audit Sample Size Calculator
Use this vendor compliance audit sample size calculator to turn operational assumptions into a transparent planning estimate. Enter values from the same scope and period, then review the main result together with the supporting metrics. The tool shows the formula, assumptions, and a worked example so you can compare scenarios without hiding the arithmetic. Results are estimates and should be checked against your organization’s policies, systems data, and operating constraints before a decision is made.
Calculator
Audit sampling inputsFormula
Initial sample n₀ = z²p(1−p) ÷ e². Finite-population sample n = n₀ ÷ [1 + (n₀−1) ÷ N], rounded up.
What the result means
The sample estimates a population proportion at the selected confidence and margin under simple random sampling.
This statistical estimate does not replace risk-based audit judgment or requirements for specific high-risk vendors.
Example calculation
For 1,200 vendors, 95% confidence, 5% margin, and 50% expected proportion, the finite-population sample rounds up to 292 vendors.
Tips for better results
- Use 50% when no prior proportion estimate exists; it is conservative.
- Randomize selection across the full in-scope population.
- Increase coverage for separately identified high-risk strata.
- Document exclusions and nonresponses.
Frequently asked questions
Which inputs have the greatest effect on this vendor compliance audit sample size calculator?
Inputs that multiply the main formula or form its denominator have the most direct effect; change one input at a time to see its influence.
Can I use zero in this calculator?
Zero is accepted where it represents a valid absence, but required denominators and capacity inputs must be greater than zero.
Should all inputs cover the same time period?
Yes. Any cost, workload, output, or shipment figures must use a consistent period unless the field explicitly states otherwise.
Does the result guarantee an operating outcome?
No. It is an estimate based on the values entered and does not capture every operational, contractual, or regulatory constraint.
How should I compare two scenarios?
Keep the scope and units constant, change only the assumption being tested, and compare the main and secondary results.
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Input and unit reference
| Input | Unit |
|---|---|
| Vendor population | vendors |
| Confidence level | % |
| Margin of error | % |
| Expected exception rate | % |