The short answer is “there is no tolerance”. The net quantity of content statement must be accurate, but reasonable variations are permitted. These variations are permitted only when caused by unavoidable deviations that occur in current good manufacturing and quantity control practices. A sample must “pass” two requirements: the Average Requirement and the Individual Package Requirement. A sample “fails” if either requirement is not met.
The Average Requirement means that the average net quantity of contents of packages in a lot must at least equal the net quantity of contents declared on the label.
The Individual Package Requirement states that the variation of individual package contents from the labeled quantity must not be “unreasonably large.” Packages that are under filled by more than the Maximum Allowable Variation (MAV) specified for the package are considered unreasonable errors. Unreasonable shortages are not generally permitted, even when overages in other packages in the same lot, shipment, or delivery compensate for such shortage. These unreasonable minus errors , or errors that exceed the MAV are based on the labeled quantity and are found in Tables in Appendix A, of NIST Handbook 133, Checking the Net Content of Packaged Goods.
For more information, it is recommended that you read Chapter 1, General Information, found in NIST Handbook 133, Checking the Net Contents of Packaged Goods. 2023 NIST Handbook 133 Chapter 1
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