Estimate a defensible planning sample size for contract review work. Adjust the operational and scenario assumptions to see a transparent main result, supporting metrics, and practical interpretation. This independent planning tool does not determine legal obligations or replace advice from qualified counsel.
The usable sample is the estimated number of completed tests needed for the selected precision assumptions; the draw size adds an allowance for unavailable or unusable items.
This calculator estimates a random-sample size for a proportion. It does not replace a regulator-mandated method, stratification, discovery protocol, or professional sampling judgment.
For 10,000 items, 95% confidence, 5% margin of error, 50% expected exceptions, and 10% unusable items, the usable sample is 370 and the initial draw is 412 items.
A 50% proportion produces the most conservative sample size when the true rate is unknown.
No. After populations become large, precision and confidence influence sample size more than population growth.
It covers selected items that are missing, inaccessible, duplicated, or otherwise unsuitable for testing.
The formula assumes random selection; judgmental or targeted samples need a different interpretation.
Not necessarily. Follow any mandated protocol and obtain qualified legal or statistical advice.
| Input | Role in the estimate |
|---|---|
| Population size | User-entered scenario assumption |
| Confidence level | User-entered scenario assumption |
| Margin of error | User-entered scenario assumption |
| Expected exception rate | User-entered scenario assumption |
| Unusable sample allowance | User-entered scenario assumption |