Container load calculator: CBM, weight and units per container
Enter the packed size and weight of one unit and the quantity. The calculator returns the total CBM, the total weight, and how many units fit in a 20ft, 40ft and 40ft high cube container.
Open the calculatorRequest a quoteHow do you calculate CBM and container load?
Calculate your load
Use the outer dimensions of one packed unit: the carton, crate, pallet or machine skid as it will be loaded.
Container dimensions used in this calculator
These are typical values. They vary by carrier, by container manufacturer and by the age of the container.
| Container | Inside length × width × height | Door opening width × height | Internal volume | Maximum payload |
|---|---|---|---|---|
| 20ft standard | 590.0 × 235.2 × 239.5 cm | 234.0 × 229.2 cm | 33.2 CBM | 28,130 kg |
| 40ft standard | 1,203.2 × 235.2 × 239.5 cm | 234.0 × 229.2 cm | 67.7 CBM | 28,750 kg |
| 40ft high cube | 1,203.2 × 235.0 × 270.0 cm | 234.0 × 259.7 cm | 76.3 CBM | 28,600 kg |
Source: example specifications published by one carrier, Hapag-Lloyd (20ft, 40ft, 40ft high cube), checked on 7 October 2026. The carrier states that its figures are examples and that containers vary by manufacturer. Road and port weight limits in the country of loading or delivery can be lower than the rated payload of the container. We are not affiliated with any shipping line.
How the calculation works
- Volume. Unit CBM is length × width × height in centimetres divided by 1,000,000. Total CBM is unit CBM multiplied by the quantity.
- Fit by size. Units are placed in straight rows, all facing the same way. The calculator tries each direction you allow and keeps the one that fits the most units. With “keep upright” ticked, a unit is only turned on the floor, never tipped onto a side.
- Door check. A unit must pass through the door opening, which is lower and slightly narrower than the inside of the container.
- Fit by weight. The maximum payload divided by the unit weight gives the number of units the container can carry.
- Result. The smaller of the two numbers is the units per container. Your quantity divided by that number, rounded up, is the number of containers needed.
What the calculator leaves out
| Not included | Why it matters |
|---|---|
| Packing you have not measured | Pallets, crates, skids and protective wrapping add to every dimension and to the weight. Enter the size and weight of the unit as packed. |
| Blocking, bracing and lashing | Machinery is secured with timber and straps that take up floor space. A machine that fits on paper with a few centimetres to spare may not fit in practice. |
| Mixed directions and mixed sizes | A load planner can turn some units to fill gaps, and can combine different items. The calculator handles one unit size, all facing one way, so a professional plan may fit a few more. |
| Weight distribution and floor loading | Heavy items must be spread along the container floor. One very heavy machine can need load-spreading timber even when it is under the payload limit. |
| Local weight limits | Truck and road limits at either end can be lower than the container payload. Check with your forwarder. |
Buying from Korea? See Korea export sourcing for how orders work, and used machinery from Korea for dismantling, packing and loading of machines.
Frequently asked questions
What is CBM?
CBM means cubic metre, the unit of volume used to quote sea freight. One CBM is a space 1 m long, 1 m wide and 1 m high. For a box measured in centimetres, multiply length × width × height and divide by 1,000,000.
How many CBM fit in a 20ft and a 40ft container?
By the example specifications used here, the internal volume is 33.2 CBM for a 20ft standard, 67.7 CBM for a 40ft standard and 76.3 CBM for a 40ft high cube. Cargo rarely fills all of it, because whole units leave gaps at the walls, the roof and the door.
Does a 40ft container carry twice the weight of a 20ft?
No. A 40ft container has about twice the floor length, but its rated payload is close to that of a 20ft: 28,750 kg against 28,130 kg in the example specifications used here. Dense cargo reaches the weight limit long before a 40ft is full, which is why heavy goods often ship in 20ft containers.
Why do fewer units fit than the CBM suggests?
Dividing container volume by unit volume assumes the cargo can fill every gap. Real units are loaded whole, so the space left over at the end of a row or under the roof is lost. The calculator counts whole units in rows.
What if my machine is too tall or too wide for the door?
The calculator shows “does not fit”. Cargo that is too large for a standard or high cube container usually moves on special equipment such as an open-top or flat-rack container, or as break bulk. Availability depends on the carrier and the route, so this is checked when the shipment is quoted.
Does the result include pallets?
Only if you enter the dimensions and weight of the loaded pallet as one unit. The calculator does not add pallet height or weight for you.
Request a quote
Tell us what you need. We reply in English within one business day.
The buttons open your email app or WhatsApp with the request filled in. You can also write to ohytto@naver.com. Export sourcing on Unboxing Korea is handled by HANA for U, a trading company based near Incheon, Korea.
