Two shipments can weigh exactly the same and cost very different amounts to move. A pallet of steel parts and a pallet of foam cushions might both weigh 300 kg, but the cushions take up several times the space in a container or aircraft hold. That is why carriers price freight on both weight and volume, and why every quote you request needs accurate carton dimensions.
This guide covers the formulas forwarders use, so you can check a quote, compare air and ocean options, and decide when a shared container stops making sense.
Step 1: measure your cartons correctly
Measure the outside of the packed carton or pallet, including any overhang, at its longest, widest and tallest points. For palletised freight, include the height of the pallet itself. Round up, not down: carriers measure freight at the terminal, and if their numbers are larger than yours, the invoice follows their numbers.
Step 2: calculate CBM (cubic metres)
CBM is simply volume in cubic metres:
CBM per carton = length (m) × width (m) × height (m)
Total CBM = CBM per carton × number of cartons
If you measure in centimetres, multiply the three dimensions and divide by 1,000,000.
Example: 120 cartons, each 60 cm × 40 cm × 45 cm.
60 × 40 × 45 = 108,000 cm³ = 0.108 m³ per carton.
0.108 × 120 = 12.96 CBM.
If you work in inches, multiply length × width × height and divide by 61,024 to get cubic metres.
Step 3: LCL ocean freight and the weight-or-measure rule
For less-than-container-load ocean freight, rates are quoted per "revenue tonne" (sometimes written W/M, weight or measure). One revenue tonne is 1 cubic metre or 1,000 kg, whichever is greater.
- A shipment of 5 CBM weighing 1,800 kg is billed as 5 revenue tonnes (volume is greater).
- A shipment of 2 CBM weighing 3,500 kg is billed as 3.5 revenue tonnes (weight is greater).
Most general cargo is billed on volume. Many LCL services also apply a minimum charge, often 1 CBM, so very small shipments cost the same as one cubic metre. Remember that origin handling, destination CFS (deconsolidation) charges and customs are separate from the ocean rate; see FCL vs LCL shipping to Canada for the full cost picture.
Step 4: when to switch from LCL to a full container
Standard containers hold roughly the following internal volume. Real loadable space is lower, because cartons rarely fill every corner:
| Container | Approx. internal volume | Practical load (typical) |
|---|---|---|
| 20' standard | about 33 m³ | about 25 to 28 m³ |
| 40' standard | about 67 m³ | about 55 to 58 m³ |
| 40' high cube | about 76 m³ | about 65 to 68 m³ |
Because LCL carries per-CBM charges at both ends, a full container often becomes the better deal well before it is full. We usually start comparing FCL once a shipment reaches about 13 cubic metres. In the example above, 12.96 CBM is right at that point, so it is worth pricing both. A 20' container also caps weight, so very dense cargo can reach the weight limit before the box is full. Your forwarder can confirm the payload for the specific equipment.
Step 5: air freight chargeable weight
Airlines charge on chargeable weight, which is the greater of the actual gross weight and the volumetric (dimensional) weight. The standard air cargo divisor is 6,000:
Volumetric weight (kg) = length × width × height (cm) ÷ 6,000
That works out to about 167 kg per cubic metre. If your cargo is lighter than 167 kg per CBM, you will pay for volume rather than weight.
Example: 10 cartons, each 50 × 40 × 40 cm and 9 kg.
Volumetric weight per carton: 50 × 40 × 40 ÷ 6,000 = 13.33 kg.
Total volumetric weight: 133.3 kg. Total actual weight: 90 kg.
Chargeable weight: 133.5 kg (airlines usually round up to the next half kilogram).
Quotes for air freight to Canada are calculated on this figure, so packaging matters. Oversized cartons with void fill can add a lot of cost on a long-haul lane.
Step 6: courier and express shipments
Express couriers generally use a smaller divisor, commonly 5,000 (about 200 kg per CBM), which makes light, bulky parcels even more expensive by courier than by consolidated air freight. Check the divisor in your courier's terms, because it varies by carrier and service. For samples and small urgent parts, express is still often the fastest option.
Step 7: trucking and density
For domestic and cross-border ground freight, LTL pricing in Canada is commonly based on weight, pallet space or a density-based rating, and carriers may apply a minimum density or a linear-foot rule for freight that cannot be stacked. Tell the carrier if pallets are non-stackable, because that changes how much trailer space you are using.
A quick checklist before you request a quote
- Number of cartons or pallets
- Dimensions of each type of package, in cm or inches
- Gross weight per package and in total
- Whether pallets can be stacked
- Commodity description, and any batteries, liquids or dangerous goods
Send those details through our freight quote form and we will calculate CBM and chargeable weight for each mode, so you can compare ocean, air and trucking on a like-for-like basis.
Frequently asked questions
How do I calculate CBM for a shipment?
Multiply the length, width and height of one carton in metres to get its CBM, then multiply by the number of cartons. If you measure in centimetres, divide length × width × height by 1,000,000 to convert to cubic metres.
What is chargeable weight in air freight?
Chargeable weight is the greater of the actual gross weight and the volumetric weight. For air cargo, volumetric weight is length × width × height in centimetres divided by 6,000, about 167 kg per cubic metre.
How is LCL freight charged?
LCL ocean freight is charged per revenue tonne: 1 cubic metre or 1,000 kg, whichever is greater. Most services also have a minimum charge, often 1 CBM, plus separate origin, destination and customs charges.
How many CBM fit in a 20 ft or 40 ft container?
A 20 ft container has about 33 m³ of internal space and typically loads around 25 to 28 m³ of cartons. A 40 ft holds about 67 m³ (about 55 to 58 m³ loaded) and a 40 ft high cube about 76 m³ (about 65 to 68 m³ loaded).
When is a full container cheaper than LCL?
It depends on the lane and charges, but full container pricing is worth comparing once a shipment reaches about 13 cubic metres, because LCL charges per cubic metre at both origin and destination.