Before you book a full container load (FCL), it helps to know how many CBM (cubic meters) will actually fit. Every container has two numbers. The nominal capacity is the volume of the empty container, and it’s the figure on carrier spec sheets. The usable capacity is what you can really stow once boxes meet walls, roof and doors, and it’s always lower.
| Container | Nominal capacity | Usable capacity, boxes |
|---|---|---|
| 20’ standard (dry) | 33.2 m³ | about 25–28 CBM |
| 40’ standard (dry) | 67.7 m³ | about 52–58 CBM |
| 40’ High Cube | 76.3 m³ | about 60–68 CBM |
The usable ranges are industry rules of thumb for floor loaded boxes (stacked directly on the container floor, no pallets), not guaranteed figures. The gap matters because it ends up on an invoice: shippers who order containers based on nominal capacity, and freight forwarders who quote from it, keep running into the same expensive mistake.
Where nominal capacity comes from
Nominal capacity is the product of a container’s internal dimensions: inside length × width × height. A carrier’s 20’ standard container measuring 5.900 × 2.352 × 2.395 m works out to about 33.2 m³. In cubic feet, the three standard sizes come to about 1,172, 2,390 and 2,694 ft³. Full specs for each type are in our container dimensions guide.
ISO 668 sets external dimensions, minimum internal dimensions and upper limits for maximum gross weight. It doesn’t fix one exact inside size, but it keeps carriers close enough that their nominal capacities are nearly identical. Two carriers list the 20’ at 33.2 and 33.1 m³, the 40’ at 67.7 and 67.6 m³, and the 40’ high cube at 76.3 and 76.2 m³.
The trouble is that boxes are rigid. If a box’s length, width or height doesn’t divide evenly into the inside of the container, space is left over along the walls, under the roof and at the door end. That leftover is called broken stowage, or simply wasted space. In a 40’ standard container rated at 67.7 m³, boxes usually fill about 55 CBM.
What decides how much you can actually load
Four things set the usable figure: how well your boxes fit, whether they can be rotated, whether they’re on pallets, and how heavy they are.
1. Box dimensions
This is the biggest variable, and no formula replaces an actual load plan. In the same container, utilization can range from about 70% to well over 80%, depending only on box size.
Take a 60 × 40 × 40 cm box (0.096 CBM) in a 40’ standard container. Stacked in a single orientation and kept upright, 500 boxes fit: 48.0 CBM, or 70.9% of nominal capacity. Let the boxes rotate and mix orientations, as our Container Loading Calculator does, and 550 fit: 52.8 CBM, or 78.0%. A 50 × 35 × 30 cm box fits better still. With rotation allowed, 1,120 go in (58.8 CBM, 86.9%). If they must stay upright, 1,008 (52.92 CBM, 78.2%).
2. Whether boxes can be rotated
Boxes marked “this side up” must stay upright, so their height axis is locked. As a rule of thumb, that costs 3–10 percentage points of utilization. In the calculator, the 60 × 40 × 40 cm box loses 7.1 points between the two results above, and the 50 × 35 × 30 cm box loses 8.7 points in a 40’ standard container. The same 50 × 35 × 30 cm box loses nothing in a 40’ high cube.
3. Pallets or floor loaded
A pallet takes up floor space and height of its own, and its footprint rarely matches the container floor. Palletized loads typically use about 50–65% of nominal capacity. Floor loaded boxes reach about 70–85%. In a 40’ container, that difference is usually 10 CBM or more. If your cargo has to go on pallets, see how many pallets fit in a container.
4. Payload
Heavy cargo can reach the weight limit before the space is full. Our calculator uses a payload of 28,200 kg for a 20’ standard, 28,800 kg for a 40’ standard and 28,620 kg for a 40’ high cube. Actual limits vary by carrier and by the container’s maximum gross weight rating: comparing the same carrier’s 40’ and 20’, the 40’ can carry anywhere from 620 kg more to 1,490 kg less.
For a 20’ standard container to hit 28,200 kg with less than half its space used, the cargo has to be denser than about 1,700 kg/m³ (28,200 ÷ 16.6). Ceramic tiles are a typical case. At an assumed density of about 2,000 kg/m³, a 40’ standard container takes 28,800 ÷ 2,000 = 14.4 CBM of tiles before it’s at its limit, only about 21% of its 67.7 m³.
Weight also has to be declared. Under the SOLAS rules set by the IMO, every packed container needs a Verified Gross Mass (VGM), however full it is. There are two ways to get it: weigh the packed container on calibrated, certified equipment, or weigh all the cargo, packaging, pallets, dunnage and securing material and add the container’s tare weight, using a method approved in the country where the container is packed. More in our guide to container weight limits and VGM.
Usable CBM by cargo type
Use this table as a starting point. Figures are in CBM.
| Cargo type | 20’ standard | 40’ standard | 40’ High Cube |
|---|---|---|---|
| Same-size boxes, rotation allowed | 26–28 | 52–58 | 62–68 |
| Same-size boxes, must stay upright (this side up) | 24–26 | 52–55 | 58–63 |
| Palletized (euro pallet 120 × 80 cm or standard pallet 48” × 40”) | 18–22 | 38–45 | 42–50 |
| Mixed box sizes, hand loaded | 22–25 | 48–54 | 54–60 |
These are planning figures, not guarantees. Before booking, run the numbers with your actual box dimensions.
Worked example: 63 CBM that looks like a 40’
Suppose you have 1,200 boxes, each 50 × 35 × 30 cm and 7 kg.
- Volume per box: 0.5 × 0.35 × 0.3 = 0.0525 CBM
- Total volume: 0.0525 × 1,200 = 63 CBM
- Total weight: 7 × 1,200 = 8,400 kg
On nominal capacity, a 40’ standard container (67.7 m³) looks like it has room to spare. On usable capacity, it doesn’t. With rotation allowed, a 40’ standard container holds about 52–58 CBM, well short of 63. A 40’ high cube holds about 62–68 CBM, so 63 fits, but without much margin. If the boxes had to stay upright, the high cube planning range would be 58–63, and 63 sits right at the top.
That’s close enough to calculate rather than guess. The calculator fits all 1,200 boxes in a 40’ high cube. A maximum-load run for the same box gets 1,296 boxes in: 68.04 CBM, or 89.2% of nominal capacity, with or without rotation. At 9,072 kg, that’s far below the 28,620 kg payload, so the container runs out of space before reaching the weight limit.
A 40’ standard container falls short. With rotation allowed, it takes at most 1,120 boxes, leaving 80 boxes (4.2 CBM) behind. If they must stay upright, the limit is 1,008, leaving 192 boxes (10.08 CBM).
So if you book a 40’ standard on nominal capacity, about 4–10 CBM won’t go in and has to travel as a separate LCL shipment. That means paying per cubic meter or per 1,000 kg, whichever is greater, plus a second set of origin charges, paperwork and destination handling. The leftover may also sail on a different vessel and clear customs separately. On many trade lanes, that tends to cost more than the extra charge for a 40’ high cube would have.
Four common capacity mistakes
Quoting on nominal capacity. Promise a customer 67 CBM per 40’ and about 10 CBM (9–15, against a usable 52–58) physically won’t fit. Either the seller absorbs the cost or it turns into a contract dispute.
Ignoring payload on dense cargo. Tiles at about 2,000 kg/m³ max out a 40’ on weight at just 14.4 CBM. Buying space by the CBM for cargo like this means paying for volume you can’t use, and loading to the space rather than the weight risks overweight fees at the terminal and overweight fines on the road.
Forgetting the door opening. The door is lower than the inside of the container: 228 cm against 239 cm in a standard container, and 257.7 cm against 270 cm in a high cube. Plan the height of your load to the door opening, not the internal height.
Counting pallet CBM as box CBM. Adding up the outside volume of loaded pallets counts the air between the boxes and the pallet edges twice. Plan container capacity on box CBM. Pallet CBM is for LCL charges and warehouse storage.
Ways to win back some of that space, through box orientation, box size and the pallets-or-floor decision, are covered in our guide to maximizing container space.
Non-standard equipment and smaller losses
45ft high cube. A 45ft high cube offers about 86.1 m³ of nominal capacity (one carrier lists 86.0 m³). It’s only offered on some trade lanes, and availability and rates vary a lot.
Oversized cargo. If something won’t pass through the door opening, you’re looking at an open top or flat rack for out-of-gauge (OOG) cargo, meaning oversized cargo that exceeds the container’s dimensions. Then CBM stops being the constraint. Securing, gauge and crane access take over.
Dunnage. Airbags, corner protectors and desiccants take up about 1–2% of the loaded volume.
When to move up a container size
Based on the real CBM of your cargo:
- Over about 26 CBM: a 20’ standard is at risk. Get a quote for a 40’.
- Over about 56 CBM: get a quote for a 40’ high cube, which adds 8.6 m³ of nominal capacity.
- Over about 66 CBM: plan on two containers, or change the box design.
These thresholds sit near the top of the usable ranges above and are rules of thumb. Heavy cargo that reaches the weight limit first gets nothing from a high cube’s extra height.
At the other end, below about 13–15 CBM a full container may not make sense. Compare it with LCL and find the point where both options cost the same, as explained in FCL vs. LCL.
How many CBM fit in a 40ft container?
A 40’ standard dry container has a nominal capacity of 67.7 m³, but that’s the empty box. Floor loaded boxes (stacked straight on the container floor, no pallets) usually fill about 52–58 CBM. On pallets, plan on about 38–45 CBM. These are planning figures, not guarantees: the real number depends on your box dimensions, so check it with a load plan before booking.
How many CBM fit in a 20ft container?
A 20’ standard dry container is rated at 33.2 m³. In practice, floor loaded boxes usually fill about 25–28 CBM. Treat that as a planning range rather than a guarantee, because the exact figure depends on how well your box dimensions fit the inside of the container.
How many CBM fit in a 40ft high cube container?
A 40’ high cube has a nominal capacity of 76.3 m³, and floor loaded boxes usually fill about 60–68 CBM. It has the same floor as a 40’ standard container but is taller inside, which is where the extra space comes from.
Why can’t you load the full nominal CBM of a container?
Boxes are rigid. Unless their length, width and height divide evenly into the inside of the container, gaps are left along the walls, under the roof and at the door end. Boxes that must stay upright (this side up) can’t be turned to fill those gaps, pallets take up floor space and height of their own, and heavy cargo can reach the payload limit before the space is full. That’s why a container rated at 67.7 m³ usually holds about 52–58 CBM of boxes.
Is a 40ft high cube better than a standard 40ft container?
For light, bulky cargo, usually yes. A 40’ high cube gives you 8.6 m³ more nominal capacity (76.3 vs. 67.7 m³) for a small extra charge. For heavy cargo that reaches the weight limit before the space is full, the extra height adds nothing, because the payload doesn’t go up.
How many boxes fit in a 20ft container?
It depends entirely on the box size. For a 60 × 40 × 40 cm box (0.096 CBM), our Container Loading Calculator fits 258 boxes in a 20’ standard container with rotation allowed, which is 24.77 CBM or 74.6% of the nominal capacity. Working from the 25–28 CBM planning range instead gives roughly 260–290 boxes. The calculated result falls just below that range, which is why it’s worth running your own box dimensions.
Does a 40ft container hold twice as much as a 20ft?
By volume, slightly more than twice: 67.7 m³ against 33.2 m³. By weight, no. The payload is almost the same (28,800 kg vs. 28,200 kg in our calculator), and depending on the carrier and the container’s maximum gross weight rating, a 40’ can even carry less than a 20’. Heavy cargo gains very little from moving up to a 40’.
How much space do you lose by palletizing a container load?
Usually 10 CBM or more in a 40’ container. Palletized loads typically use about 50–65% of the nominal capacity, compared with about 70–85% for floor loaded boxes. In planning terms, a 40’ standard container holds about 38–45 CBM on pallets against 52–58 CBM floor loaded.