What is a freight ton (W/M)?
A freight ton, also called a revenue ton, is the unit LCL and breakbulk ocean freight is charged on: the higher of the cargo's weight in metric tonnes and its volume in cubic metres. W/M stands for weight or measurement, whichever is greater.
The rule treats 1 tonne and 1 cbm as equal. Dense cargo, such as steel coils or castings, pays on its weight; light, bulky cargo, such as crated machinery or insulation panels, pays on its volume. A rate of USD 45 W/M means USD 45 for every freight ton.
How do you calculate cbm?
Multiply length × width × height in metres for one piece, then multiply by the number of pieces. Convert first: centimetres ÷ 100, millimetres ÷ 1,000.
- A crate of 240 × 120 × 150 cm is 2.40 × 1.20 × 1.50 = 4.32 cbm.
- Ten cartons of 600 × 400 × 400 mm are 0.60 × 0.40 × 0.40 × 10 = 0.96 cbm.
One cbm is 35.315 cubic feet. Some trades still use a measurement ton of 40 cubic feet, about 1.133 cbm; when an offer uses it, convert before you compare.
How do you work out W/M for one piece?
Work out the weight in tonnes (kg ÷ 1,000) and the volume in cbm, and take the higher of the two.
| Piece | Weight | Volume | W/M |
|---|---|---|---|
| Crate, 2.40 × 1.20 × 1.50 m | 1,800 kg = 1.80 t | 4.32 cbm | 4.32 (on volume) |
| Steel coil, 1.20 × 1.20 × 1.00 m | 9,000 kg = 9.00 t | 1.44 cbm | 9.00 (on weight) |
| Machine, 2.50 × 2.00 × 2.00 m | 10,000 kg = 10.00 t | 10.00 cbm | 10.00 (either) |
Which cargo pays on weight, and which on volume?
Divide the weight in kg by the volume in cbm to get the density. At 1,000 kg per cbm the two are equal; above it the cargo pays on weight, below it on volume.
- Usually on weight: steel plates and coils, castings, machine bases, cables on drums, stone. The steel coil above is 9,000 ÷ 1.44 = 6,250 kg per cbm.
- Usually on volume: crated machinery, panels, ducting, furniture, empty tanks and vessels. The crate above is 1,800 ÷ 4.32 = about 417 kg per cbm.
The density check is a quick way to spot a typing error: a crate of machinery at 6,000 kg per cbm, or a steel coil at 200, is almost certainly a wrong unit or a wrong digit.
How do you calculate W/M for an LCL shipment?
Take six pallets, each 1.20 × 1.00 × 1.10 m and 450 kg:
- Volume: 1.20 × 1.00 × 1.10 = 1.32 cbm per pallet, × 6 = 7.92 cbm.
- Weight: 450 × 6 = 2,700 kg = 2.70 t.
- W/M: the higher of the two, 7.92.
- Freight at an illustrative USD 40 per W/M: 7.92 × 40 = USD 316.80.
LCL offers usually carry a minimum, often 1 W/M, and the origin and destination charges are often quoted per W/M too. Read the offer for both.
Per piece or on the total: does it matter?
It can. Take two pieces in one shipment:
| Piece | Weight | Volume | W/M per piece |
|---|---|---|---|
| Transformer, 3.00 × 2.00 × 2.50 m | 24.00 t | 15.00 cbm | 24.00 |
| Cooler, 4.00 × 2.50 × 2.00 m | 3.00 t | 20.00 cbm | 20.00 |
| Shipment | 27.00 t | 35.00 cbm | 44.00 per piece · 35.00 on the totals |
Piece by piece, the shipment is 24 + 20 = 44 freight tons. On the totals it is the higher of 27 t and 35 cbm: 35 freight tons. The heavy transformer pays on weight and the bulky cooler on volume, and adding them up per piece counts both.
Moviqo's cargo check works per piece and adds the pieces up, which gives the higher, safer figure for quoting. Some offers work on the shipment total instead. Ask which basis the line uses, and compare offers on the same one.
How is air freight different?
Air freight uses chargeable weight instead of freight tons: the higher of the actual weight and the volumetric weight. Most airlines work volumetric weight as length × width × height in cm ÷ 6,000, which is about 167 kg per cbm.
- The crate above, 240 × 120 × 150 cm and 1,800 kg: 4,320,000 ÷ 6,000 = 720 kg volumetric, so it is charged on 1,800 kg.
- A light carton, 120 × 100 × 100 cm and 120 kg: 1,200,000 ÷ 6,000 = 200 kg volumetric, so it is charged on 200 kg.
Road moves in India are usually quoted per trip, per ton or per km rather than per freight ton.
Which mistakes cost money?
- Mixing units. A crate entered as 240 × 120 × 150 "m" instead of cm becomes 4.32 million cbm; one in mm read as cm is a thousand times too big.
- Forgetting the quantity. The volume of one piece quoted for ten.
- Rounding before multiplying. 2.43 × 2.43 × 2.43 m is 14.35 cbm; rounded to 2.4 m a side it is 13.82 cbm.
- Comparing different bases. A per-piece offer and an on-the-total offer are not the same price for the same cargo.
- Reading "per ton" loosely. Check whether the offer means metric tonnes or W/M.
- Leaving out the packing. Skids, crates and saddles add weight and size; quote on packed dimensions.
For which equipment a piece needs in the first place, see OOG cargo: flat rack, open top or breakbulk? The glossary defines CBM, W/M and chargeable weight in one line each.