How Do You Calculate Net Weight?
The net weight formula needs two numbers: the weight of the packed item and the weight of its packaging.
- Weigh the packed item. Put the full package on a scale. That reading is the gross weight.
- Find the tare. Weigh an identical empty package with all its wrapping, inserts and labels, or use the packaging supplier's stated weight. That is the tare weight.
- Subtract. Gross weight minus tare weight leaves the net weight of the product.
The same arithmetic runs the other way: gross weight = net weight + tare weight. Say 40 cartons, each holding 10.0 kg of product in 1.2 kg of packaging, go out on a 20 kg pallet. Net weight is 40 × 10.0 kg = 400 kg. Tare is 40 × 1.2 kg for the cartons plus 20 kg for the pallet, 68 kg in all. Gross weight is 400 kg + 68 kg = 468 kg.
Net Weight vs. Gross Weight vs. Tare Weight
Net weight is the product alone, tare is everything else in the package, and gross weight is the two together.
In shipping, "actual weight" means the scale weight of the packed parcel or shipment, which is its gross weight. FedEx's standard pricing, for one, uses that or dimensional weight, whichever is greater, not the net weight of the product inside.
Does Net Weight Include Packaging?
No. US federal food labeling rules say the net quantity declaration must show "the quantity of food in the package exclusive of wrappers and other material packed therewith" (21 CFR 101.7).
Where Net Weight Is Used
- Consumer labels: the Fair Packaging and Labeling Act requires packages of the consumer goods it covers to state the net quantity of contents on the principal display panel, in US customary units and, with some exceptions, metric units too.
- Food labels: on food packages under 4 pounds or 1 gallon that are labeled by weight, FDA rules require the term "net weight", written for example as "Net wt. 6 oz".
- Invoices and packing lists: US import rules require each invoice to give the quantities "in the weights and measures" of the country of shipment or of the United States, and a packing list breaks those quantities down by package.
- Customs entries: on the US entry summary, CBP Form 7501, the importer reports the gross shipping weight in kilograms and the net quantity in the unit of measure the tariff line sets, such as kilograms.
- Warehousing and fulfillment: product records hold each unit's net weight for labels and listings, and the packed weight of each carton and pallet for rating shipments.