CBM Calculator

Turn carton size and count into total CBM, chargeable weight for air and sea, and container fill percentage.

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Weight per carton

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cartons

Container fill (optional)

Container (for fill %)

Practical load factor

Cartons rarely fill 100% of a container's nominal volume once pallets, odd shapes and stacking limits are accounted for. 75-90% is a common working range for floor-loaded cartons.

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Total shipment volume

5.04 CBM

120 cartons × 0.042 m³ each = 5.04 m³, weighing 960 kg in total.

Chargeable weight (air): 960 kg
Chargeable weight/measure (sea LCL): 5.04 W/M
Average density: 190.5 kg/m³

There's room left in this container. Adding more cartons, or moving to a smaller container, would use the space better.

Breakdown

Carton volume: 0.042 m³
Cartons: 120
Total volume (CBM): 5.04 m³
Total weight: 960 kg
Volumetric weight for air (CBM × 166.7, IATA's ÷6000 rule): 840 kg
Chargeable weight for air (the higher of the two): 960 kg
Chargeable weight/measure for sea LCL (1 CBM = 1,000 kg): 5.04 W/M
20ft standard nominal capacity: 33.2 m³
Container fill (of nominal capacity): 15.2%
Practical capacity at 82% load factor: 27.2 m³
Container fill (practical): 18.5%

CBM, and the two ways freight actually gets billed

CBM (cubic meters) is just length × width × height, converted to volume. But freight is rarely billed on volume alone: air cargo is billed on chargeable weight (the greater of actual and volumetric weight), and ocean LCL is billed on W/M (the greater of the CBM and the weight in tonnes, since 1 CBM is treated as 1,000 kg).

CBM = (length × width × height, in cm) ÷ 1,000,000 × number of cartons

Air chargeable weight = max(actual weight, CBM × 1,000,000 ÷ 6,000)

IATA's standard divisor is 6,000 cm³ per kg, equal to about 167 kg per m³.

Example: the default numbers (120 cartons, 40 × 30 × 35 cm, 8 kg each)

Volume per carton: 0.042 m³
Total volume: 0.042 × 120 = 5.04 CBM
Total weight: 8 × 120 = 960 kg
Volumetric weight for air: 5.04 × 166.7 = 840 kg

The shipment weighs more than its volume implies, so air freight would charge on the actual 960 kg, not the 840 kg volumetric figure. By sea, it's a small load: only 15.2% of a 20ft container's nominal volume.

Using the number with a forwarder

Air freight quotes are per kg of chargeable weight. A light, bulky product (toys, lampshades, apparel) usually gets charged on volume; a heavy, dense one (tools, electronics) gets charged on actual weight.
Ocean LCL quotes are per CBM or per W/M, often with a 1 CBM minimum. Below about 15 CBM, LCL is usually cheaper than booking a part-used full container.
Full container loads (FCL) are priced per container regardless of how full it is, so the fill % here tells you whether you're paying for space you don't use. See the container loading calculator for how many cartons actually fit, including stacking limits.

What throws the number off

Outer carton, not product size. Always measure the shipping carton, including any pallet if it ships palletized.
Practical vs nominal container capacity. A container's nominal volume assumes it's packed with no gaps. Real cartons rarely achieve that; the practical load factor here defaults to 82%, a common working assumption.
Mixed cartons. If your shipment has more than one carton size, run each size through separately and add the totals.

Questions people ask

How do I calculate CBM from carton dimensions?

Multiply length × width × height in centimeters, divide by 1,000,000 to get cubic meters, then multiply by how many cartons you have.

What is chargeable weight?

The weight a carrier actually bills you on: the greater of the shipment's actual weight and its volumetric (dimensional) weight. Light, bulky cargo is billed on volume; heavy, dense cargo is billed on actual weight.

Why does air freight use a different divisor than my carrier's website says?

6,000 cm³ per kg is IATA's general standard, but some airlines and couriers use 5,000 or 4,000 for their own express or domestic services. Check your carrier's own rate sheet if the number looks off.

How full does a container need to be to be worth booking FCL over LCL?

There's no fixed rule, but many forwarders find FCL starts beating LCL somewhere around half a 20ft container's volume, because LCL's per-CBM rate and handling fees add up. Get quotes for both at your actual volume.

Does CBM include the pallet the cartons sit on?

Only if you measure the palletized load as a whole. If you're shipping loose cartons that get palletized at origin, measure the cartons; use the pallet calculator if you need the palletized footprint instead.

Last reviewed 30 September 2026.

Sources: Wikipedia: Dimensional weight (IATA's ÷6,000 air freight formula) · Maersk: Air cargo chargeable weight · iContainers: 40-foot container dimensions and capacity