FDA Net Weight Tolerance and Compliance Standards

Federal law permits small, unavoidable variations between a package’s actual contents and the net weight on its label, but the tolerance operates through two firm limits: the average net quantity of a sampled batch must at least equal the declared weight, and no individual package may fall short by an unreasonable amount. That is the working definition of FDA net weight tolerance for packaged consumer goods, and it exists because filling machinery cannot hit an exact figure on every unit at production speed.¹²

The Two Tests a Package Must Pass

Compliance turns on two separate checks, and a shipment has to clear both.

The Average Requirement looks at a sample of packages together. Their average net quantity must be at least the weight printed on the label. If the average is low, the batch fails, even when some individual units look fine on their own. The rule blocks the tactic of underfilling some packages and offsetting with overfills elsewhere.²³

The Individual Package Requirement looks at units one at a time. No single package may show an “unreasonable shortage” against the labeled amount. A batch with a healthy average still fails if one package is missing too much product. This is the rule that protects a shopper from picking up the one nearly empty jar in a case that otherwise averages out.²³

Why Variation Is Allowed at All

The Fair Packaging and Labeling Act requires an accurate net quantity statement, but it accepts that high-speed filling produces small differences from unit to unit. The tolerance framework is the law’s way of distinguishing normal production variance from shortages that shortchange the buyer.¹

Inspectors apply the two tests using the National Institute of Standards and Technology’s Handbook 133, which sets out the standard sampling and testing methods state and federal officials follow. The handbook exists so a product tested in one jurisdiction is judged by the same procedure as a product tested in another.⁴

What Counts as the Net Weight on the Label

Net weight is the weight of the product alone. Wrappers, boxes, and other packaging materials do not count. The figure has to appear on the principal display panel, the face of the label a shopper is most likely to see, printed parallel to the base of the package and in a font large enough to read. Most packages must show both U.S. and metric units, with some exceptions such as food packaged at a retail store.³¹

What Happens When a Product Fails

A product that misses either test can be treated as misbranded under federal law. The FDA and other federal agencies can act against non-compliant goods, including seizure of the mislabeled items. State and local weights-and-measures officials run their own inspections and use their own legal tools to keep short-weight products from reaching consumers.¹⁵⁶

1
U.S. House of Representatives. 15 U.S.C. § 1453
2
NIST. Net Contents FAQ – Section: Handbook 133 Tolerances
3
Cornell Law School. 16 CFR § 500.25
4
NIST. NIST Handbook 133
5
GovInfo. 21 U.S.C. § 334
6
GovInfo. 21 U.S.C. § 343