What Is the Difference Between Gross, Net and Tare Weight?

What is tare weight?

Tare weight, also called unladen weight, is the weight of an empty container, crate, drum, pallet or other packaging with no cargo in it. When freight is weighed on a truck scale or weighbridge, tare can also mean the empty weight of the truck, trailer or railcar before loading.^[1]

For shipping containers, tare is a fixed, published number. U.S. rules require every intermodal container to be permanently marked with its empty weight, the maximum cargo weight it is designed to carry, and the sum of the two, all in pounds.^[2] Typical steel dry boxes on one carrier's spec sheet:^[3]

What is the difference between gross weight and net weight?

A carrier's shipping-weight guide puts it simply: net weight is the products only, and gross weight is the products plus any packaging, pallets and container, but not the truck that moves it.^[1]

The model weights and measures law that NIST publishes for states to adopt defines net weight as the weight of a commodity excluding things that are not part of it, such as containers, conveyances, bags, wrappers, packaging materials and labels. It adds a shipping-specific twist: depending on the service, packaging can count as part of the service, and the service of shipping includes the weight of packing materials.^[4] That is why a carrier bills on a weight that includes cartons and pallets, while the invoice shows the product's net weight.

Is net weight and gross weight the same?

No. Gross weight is always net weight plus whatever tare is being counted: cartons, pallets, stretch wrap, dunnage and, at container level, the box itself. The two numbers match only for goods weighed with no packaging at all. In one carrier's worked example, 1,680 kg of coffee becomes 1,980 kg once 300 kg of boxes and pallets are added, and 4,260 kg once the 20-ft container's 2,280 kg tare is included.^[1]

What is gross wt?

"Gross wt" (or G.W.) is shorthand for gross weight, the total weight of the goods with their packaging. On a packing list it usually describes the packed cartons or pallets. On a container document it means the packed container including its tare, which is the figure the shipper declares as the verified gross mass.^[5]

How to calculate tare weight

The arithmetic is the same at every level:^[1]

• Gross weight = net weight + tare weight
• Net weight = gross weight − tare weight
• Tare weight = gross weight − net weight

In practice you rarely calculate a container's tare; you read it. It is marked on the container,^[2] it appears on the owner's spec sheet,^[3] and one carrier lets shippers look it up by container number.^[1] For packaging, weigh an empty carton or pallet and multiply by the count. For a truck or railcar, weigh it empty and loaded; the model public weighmaster law in NIST Handbook 130 lets a weighmaster's certificate show the gross weight, the tare weight of the unladen vehicle or container, or both plus the resulting net weight.^[4]

Why is tare weight important?

• Ship stowage (VGM). Since 1 July 2016, SOLAS has required the shipper to provide a verified gross mass before a packed container is loaded. Under Method 2, the shipper weighs all packages and cargo, adds pallets, dunnage and other securing material, and adds the container's tare mass, using a method approved where the container was packed. A container without a VGM should not be loaded.^[5]
• Cranes and terminals. U.S. longshoring rules bar hoisting a container until the employer knows whether it is loaded or empty, and a loaded container's actual gross weight must be posted where the equipment operator can see it or provided on a stowage plan.^[2]
• Road limits. On the Interstate System the gross vehicle weight limit is 80,000 lb, with 20,000 lb on a single axle and 34,000 lb on a tandem, and the bridge formula can set a lower limit.^[6] Tractor, chassis and container tare all count against that total, which is why a box can be legal at sea and still too heavy to haul.

See how much weight a 40 ft container can carry, and if a load is already too heavy for the road, overweight load correction.

Example

A 40-ft high cube has a tare of 3,880 kg on one carrier's specs.^[3] It is loaded with 18,000 kg of goods (net) on pallets and in cartons weighing 1,200 kg. The cargo gross is 19,200 kg, and the container's VGM under Method 2 is 19,200 + 3,880 = 23,080 kg, well under the box's 32,500 kg maximum gross. Working backward, the tare of the cargo itself is 19,200 − 18,000 = 1,200 kg. On the road, the tractor and chassis are added to the 23,080 kg for the truck's gross vehicle weight, and that total, not the VGM, is what the 80,000 lb limit applies to.

Limitations

Usage varies. One carrier's guide uses "payload" as another name for net weight,^[1] while spec sheets use "maximum payload" for the most cargo a container may carry,^[3] so check which one a form means.

Published tare figures differ by owner, build and repairs. Use the marking on the actual container, not a generic table, when declaring a VGM.

NIST Handbook 130 is a model law. Each state decides whether and how to adopt it.^[4]