Container weight limits come in three layers: what the container is built to carry, what the road will let you haul, and the Verified Gross Mass (VGM) you have to declare before the box goes on a ship. On top of those, the weight has to be spread correctly inside the container. For most heavy cargo, the road is the limit you hit first.
Tare, payload, max gross and VGM
Four weight terms come up again and again, and each one means something different:
- Tare weight is the weight of the empty container. It’s marked on the door.
- Payload is the most cargo the container can structurally carry.
- Max gross (maximum gross weight) is tare plus payload. It’s the rating on the container’s CSC safety approval plate, the plate required by the International Convention for Safe Containers (CSC).
- Net weight is the weight of the goods alone, without packaging.
The VGM is a separate figure: cargo, packaging, pallets, dunnage (loose material used to support and protect cargo), securing material and the container’s tare weight, all added together.
Here’s one carrier’s spec for the three standard dry containers:
| Container type | Tare weight | Payload (max) | Max gross |
|---|---|---|---|
| 20’ standard | 2,350 kg | 28,130 kg | 30,480 kg |
| 40’ standard | 3,750 kg | 28,750 kg | 32,500 kg |
| 40’ high cube | 3,900 kg | 28,600 kg | 32,500 kg |
These are example figures from Hapag-Lloyd. Tare varies between individual containers of the same type and can change after repairs or a new floor, so the CSC plate and door markings on your actual container always take priority. Our Container Loading Calculator uses slightly different default values (for example, a 28,800 kg payload for the 40’ standard), within 70 kg of the table. Inside dimensions and tare for every type are in our container dimensions guide.
ISO 668 caps max gross at 36,000 kg for all sizes except the 10’ (the earlier cap was 30,480 kg). That’s a ceiling for the standard, not the rating of a given box. Each container’s own rating, whether 30,480 kg or 32,500 kg, is the one on its CSC plate.
Why a 40’ carries about the same weight as a 20’
A 40’ gives you twice the space of a 20’, but not twice the weight. The rating depends on the strength of the corner castings and frame, and that doesn’t scale with volume. In the table above, the 40’ standard carries just 620 kg more than the 20’. With another carrier whose 40’ is rated at 30,480 kg, the 40’ actually carries 1,490 kg less than its 20’ (26,840 kg vs. 28,330 kg).
For dense cargo, that means two 20’ containers usually carry more than one 40’.
Step 1: Check the road limit before the container rating
A container can be well within its rating and still be too heavy for the truck. Road limits cover the whole vehicle: tractor, chassis, container and cargo.
- United States (Interstate): 80,000 lb gross vehicle weight, about 36,287 kg including tractor, chassis, container tare and cargo. The limit on a single axle is 20,000 lb, on a tandem axle 34,000 lb, and the Bridge Formula governs how weight is spread across axle groups.
- European Union (international traffic): 40 t for a five- or six-axle combination. For a 40’ container in intermodal transport, a three-axle tractor with a two- or three-axle semi-trailer is allowed 44 t. National rules for domestic traffic can differ.
Once you take out the weight of the tractor and chassis, the cargo you can actually put in the container is lower. As a practical estimate, which depends on the truck and chassis and isn’t a legal figure, that works out to about 19–20 t in a 40’ and 17–19 t in a 20’ in the US, and about 25–29 t in Europe.
Check both ends of the trip. A load that’s legal at destination can still be illegal between your factory and the port of loading, and Hapag-Lloyd’s packing guidance makes the same point: road and rail limits in each country along the route must be observed. In the US, a tri-axle chassis (a three-axle container chassis used in drayage) or an overweight permit (a state permit for loads above legal weight limits) can raise the limit, but both add cost. Loads that can’t be broken down may qualify for special permits.
The rule for planning follows from all this: your real cap is the lowest road limit anywhere on the route, not the container rating. Check weight and volume together, because a heavy load reaches the weight limit before the space is full, while a light one runs out of space first. Our Container Loading Calculator shows what limits the load, weight or space. For the space side, see how many CBM fit in a container.
Worked example: the road limit binds before the container rating
Suppose you’re shipping 600 boxes, each 60 × 40 × 40 cm and 65 kg, in a 40’ standard container.
Space. A simple grid fits 500 boxes: 1203 ÷ 60 = 20 along the length, 235 ÷ 40 = 5 across and 239 ÷ 40 = 5 high, so 20 × 5 × 5 = 500. Ignoring weight and allowing rotation, the calculator fits 550 boxes (78.1% of the volume).
Container rating. Using the calculator’s 28,800 kg payload:
28,800 ÷ 65 = 443 boxes (rounded down), or 28,795 kg
The calculator stops at 443 boxes and reports weight as the limit. The volume used is 62.9%, so about a third of the container is still empty. Open this example in the calculator.
US road limit. The calculator only checks the container’s payload; it doesn’t know your road limit, so apply that yourself. Taking 19.5 t, the middle of the US practical range:
19,500 ÷ 65 = 300 boxes
The 443-box load is about 9.3 t over that estimate. The container rating allows it; the road doesn’t.
Two 20’ containers instead. The calculator fits 258 boxes in a 20’ standard. At 16,770 kg, that’s below even the low end of the 17–19 t US range, so the 20’ runs out of space before reaching the weight limit and stays road-legal. Two 20’ containers carry 516 boxes, about 1.7 times the 300 that one road-legal 40’ can take.
The calculator’s report also shows an estimated gross weight: cargo (plus pallets in palletize mode) and the container’s tare. It doesn’t include dunnage or securing material, so treat it as a lower bound and add those before you declare a VGM.
Step 2: Declare the VGM
The VGM requirement comes from an amendment to SOLAS Chapter VI, Regulation 2, adopted by the IMO and in force since July 1, 2016. Guidance for applying it is in MSC.1/Circ.1475. For the charges tied to VGM, see our guide to freight surcharges.
Who declares it. The shipper, meaning the party named as shipper on the bill of lading or sea waybill (a non-negotiable transport document), and/or the party that contracted the carriage with the carrier.
How to get it. There are two approved methods:
- Method 1: Weigh the packed container on calibrated, certified weighing equipment, such as a weighbridge.
- Method 2: Weigh all the cargo, packaging, pallets, dunnage and securing material, then add the container’s tare weight. The method has to be approved or certified by the authorities in the country where the container is packed. In the UK, that’s the MCA.
Method 2 doesn’t work for cargo that can’t practically be weighed item by item, such as scrap metal or loose grain. Use Method 1 for those.
In practice, a Method 2 VGM usually starts from the packing list: add up the box weights, add the dunnage and securing material, then add the tare shown on the container door. Keep a record of how you arrived at the figure.
When it’s due. SOLAS doesn’t set a deadline. The VGM just has to reach the carrier and terminal in time for the stowage plan. Each carrier sets its own VGM cut-off time (the deadline for submitting the figure), and it often falls before the cargo cut-off.
No VGM, no loading. Submitting a VGM in advance is a condition for loading, not a right to be loaded, and the ship’s master still has the final say. A container that arrives without one won’t go on the vessel.
Tolerance. SOLAS doesn’t set one, so it depends on the country. The UK MCA enforces ±5% or ±500 kg, whichever is greater. That margin is for enforcement; the shipper is still responsible for an accurate figure. South Korea allows ±5%. Check the rule in the country of loading rather than assuming one figure applies everywhere.
Common mistakes and what they cost
Declaring the cargo weight as the VGM. Leave out the tare and dunnage and a 40’ is understated by roughly 4 t: 3,750 kg of tare plus a few hundred kilograms of dunnage. That’s far more than the UK tolerance allows.
Using an average tare. Tare varies from container to container. Even when the gap is within tolerance, it eats into your safety margin. Use the figure on the door of the box you packed.
Loading to the container rating. A container loaded to its 28.8 t payload is well over typical US road limits and can be caught at a weigh station (a roadside weight checkpoint). Expect a fine, and you may be required to reload in the US, moving part of the cargo onto a second truck at your cost. If the numbers don’t work in one 40’, compare the cost of two 20’ containers; see FCL vs. LCL for how container pricing works.
What a wrong VGM costs. Expect reweighing and VGM amendment charges (the carrier’s fee for correcting a declared VGM), and the container may be rolled to the next sailing. Repeated errors can bring fines and closer inspection. Amounts and delays vary by carrier and port.
Step 3: Distribute the weight inside the container
Staying under every limit isn’t enough if the weight sits in the wrong place.
Floor loading. A container floor has a load limit per running meter: about 4.5 t in a 20’ and 3 t in a 40’, according to Hapag-Lloyd. To check a heavy item, divide its weight by the length it rests on. For example, 10 t ÷ 4 m = 2.5 t/m. Spread point loads (heavy weight on a small footprint) with timber bearers.
Center of gravity. Keep the load’s center of gravity in the middle of the container, both lengthwise and across. If too much weight sits toward the doors, the truck can go over its axle weight limit (the maximum weight carried on each axle) even when its gross weight is legal.
Stacking. Put heavy items at the bottom and lighter ones on top. For stacking patterns that also make better use of space, see our guide to maximizing container space.
The IMO/ILO/UNECE CTU Code, the international code of practice for packing cargo transport units, sets out these principles in detail. After an incident, it’s the standard that inspectors and insurers use to judge whether the container was packed properly.
How much weight can a 40ft container carry?
Structurally, a 40’ standard container takes about 28.8 t of cargo (one carrier lists 28,750 kg, with a 3,750 kg tare and a 32,500 kg max gross). On the road you usually get less. Practical cargo limits, which are estimates that depend on the truck and chassis, run about 19–20 t in the US and 25–29 t in Europe. Plan to the lowest limit anywhere on the route, not to the container rating.
What is the maximum weight for a 20ft container?
A 20’ standard container is typically rated at 30,480 kg max gross. With a 2,350 kg tare, that leaves a 28,130 kg payload on one carrier’s spec. US road moves usually limit a 20’ to about 17–19 t of cargo, a practical estimate rather than a legal figure. A tri-axle chassis or an overweight permit can raise that, at extra cost.
What is VGM?
Verified Gross Mass (VGM) is the total weight of a packed container: cargo, packaging, pallets, dunnage, securing material and the container’s tare weight. It’s required under an amendment to SOLAS Chapter VI, Regulation 2, in force since July 1, 2016. A container without a VGM submitted in advance won’t be loaded onto the vessel.
Why can a 40ft container carry barely more weight than a 20ft?
A container’s weight rating comes from the strength of its frame and corner castings, not from its volume. The 40’ has twice the space but a similar structure. Comparing one carrier’s boxes, a 40’ rated at 32,500 kg carries 620 kg more than its 20’. Another carrier’s 40’ rated at 30,480 kg carries 1,490 kg less. For dense cargo, two 20’ containers usually carry more than one 40’.
Who is responsible for the VGM?
The shipper is, meaning the party named as shipper on the bill of lading or sea waybill, and/or the party that contracted the carriage. The shipper gets the VGM either by weighing the packed container on calibrated, certified equipment (Method 1) or by weighing every item that goes in and adding the tare weight, using a method approved in the country of packing (Method 2).
What happens if the VGM is missing or wrong?
Without a VGM, the container won’t be loaded; the ship’s master has the final say. If the declared figure is outside the tolerance, expect reweighing and VGM amendment charges, and the box may be rolled to the next sailing. Tolerances are set by each country. The UK enforces ±5% or ±500 kg, whichever is greater. Repeated errors can lead to fines and closer inspection.
What VGM tolerance applies in the UK?
The UK Maritime and Coastguard Agency (MCA) enforces a tolerance of ±5% or ±500 kg, whichever is greater. That margin guides enforcement officers; it doesn’t lower the shipper’s duty to declare an accurate figure. SOLAS itself sets no tolerance, so other countries use their own. South Korea, for example, allows ±5%.
When is the VGM due?
SOLAS doesn’t set a deadline. The VGM has to reach the carrier and terminal in time for the stowage plan, and each carrier publishes its own VGM cut-off. That cut-off often falls before the cargo cut-off, so check the booking confirmation rather than assuming the two are the same.
Where do I find a container’s tare weight?
It’s marked on the container door. Tare varies from one container to the next, even within the same type, and can change after repairs or a floor replacement. For a Method 2 VGM, use the tare shown on the actual container you packed, not a fleet average.
Does the VGM include pallets, packaging and dunnage?
Yes. The VGM covers everything inside the container plus the container itself: cargo, packaging, pallets, dunnage, securing material and the container’s tare weight. Declaring only the cargo weight understates a 40’ by roughly 4 t.