Container weight limits: which number applies

The box rating

Every container carries a CSC plate with its maximum gross mass; subtract the tare (empty weight) and you get the payload. The same size is rated differently by different owners:

A 2,020 kg spread on the same box size. For a 20' GP the sources agree more closely (ONE 28,330 kg, SeaCube 28,340 kg payload). All ten types and their sources are on the container data sheet.

The road

On US Interstate highways the federal limit is 80,000 lb gross vehicle weight (FHWA), which is 36,287 kg for the whole vehicle: tractor, chassis, empty container and cargo. Whatever the box is rated for, the cargo has to fit inside what is left once those are subtracted, and states and other countries set their own limits. Ask the trucker or forwarder for the cargo weight they can move on your route.

The verified gross mass

Since 1 July 2016, SOLAS regulation VI/2 requires the verified gross mass of a packed container to be obtained before it is loaded on a ship, and the shipper must state it in the shipping document (IMO). The VGM is the weighed total, not an estimate from the packing list, so plan below the limit and leave room for the difference.

A dense cargo, three answers

1,000 cartons of floor tiles, 60 × 30 × 10 cm and 27 kg each: 18 m³ and 27,000 kg. Volume is not the problem (64% of a 20' GP at 85% fill); weight is.

• Box rating (SeaCube): fits one 20' GP, at 95.3% of its 28,340 kg payload.
• ONE rating: the 20' GP still fits (28,330 kg), but a 40' GP rated 26,840 kg does not: 27,000 kg needs two of them. The bigger box carries less.
• Your own limit of 20,000 kg (a road limit, for example): two 20' GP.

The Weight limit setting in the CBM calculator switches between the box rating, ONE's ratings and a figure you type; every container card and the verdict follow it.