Since the 2016 SOLAS amendment, no packed container can be loaded onto a ship without a Verified Gross Mass declared by the shipper. This calculator builds that figure with the SOLAS Method 2 calculation — summing cargo, packaging, dunnage, and the container’s own tare — and checks it against the box’s rated maximum gross mass.
How it works
The rule under SOLAS Chapter VI Regulation 2 is a simple sum:
VGM = cargo_weight
+ packaging_and_securing
+ dunnage_and_blocking
+ container_tareThe tool starts each container type from its standard tare, but you should enter the exact tare from the CSC plate when you have it. It then compares the VGM to the maximum gross mass — a structural limit also printed on the plate — and flags any overweight before you submit the booking.
Typical container tare weights and maximum gross masses
| Container type | Approximate tare | Approximate max gross mass |
|---|---|---|
| 20ft standard (ISO) | ~2,200 kg | ~24,000 kg |
| 40ft standard | ~3,700 kg | ~30,480 kg |
| 40ft High Cube | ~3,900 kg | ~28,560–30,480 kg |
| 20ft Reefer | ~3,000 kg | ~27,000 kg |
These are typical industry figures — the exact values are stamped on the CSC plate of your specific container and those are the numbers to use in your VGM declaration.
A worked example
A 40ft High Cube carries a shipment of electrical components:
- Cargo weight: 18,000 kg
- Packaging and pallets: 400 kg
- Lashing, blocking, and dunnage: 150 kg
- Container tare (from CSC plate): 3,900 kg
VGM = 22,450 kg, well under the 30,480 kg maximum, so the booking can proceed and the VGM figure is submitted to the terminal.
Now suppose the shipper also loaded 3,000 kg of battery packs not listed on the original cargo manifest. That raises VGM to 25,450 kg — still within limits, but if the terminal receives a declared VGM of 22,450 kg the container is flagged as a mismatch and can be held for re-weighing, causing delays and potentially fines.
Method 1 versus Method 2
SOLAS permits two methods:
- Method 1: Weigh the entire packed container on a certified scale. The scale reading is the VGM. Simple, accurate, and used for high-value or overweight-risk loads.
- Method 2: Sum the certified individual weights of every component — cargo items, packaging materials, dunnage, securing equipment — and add the container’s tare. This is what this calculator implements.
Method 2 requires that the individual weights come from certified or documented sources. Guessing the weight of a pallet or dunnage timber and entering it directly violates the SOLAS requirement. The calculation itself is straightforward; the compliance burden is in having certified weights for every item.
Notes
Always use the actual tare and maximum gross mass stamped on your specific container’s CSC plate, as values vary by build and age. Method 2 weights must come from certified sources. Treat the result as your declaration basis, not a substitute for legal advice or certified weighing where required by your shipping line or national regulation.