Volumetric weight is a notional weight derived from a package's size. For air cargo the formula is length × width × height (cm) ÷ 6,000; express couriers usually divide by 5,000. Freight is then charged on the chargeable weight, the greater of actual and volumetric weight. At sea the same idea appears as W/M, and on the road as a kilograms-per-cubic-metre factor.
Why volumetric weight exists
Aircraft, trucks and ships all have two limits: weight and space. Light but bulky goods such as pillows, lamps or empty cartons fill the space long before they reach the weight limit. Without volumetric weight, carriers would lose money on space taken by cargo that pays very little. Tariffs therefore charge on whichever is "heavier" for the carrier: the mass or the space. Short definitions are in the glossary under volumetric weight and chargeable weight.
Factors by transport mode
The conversion factor sets how many kilograms one cubic metre is deemed to weigh. The higher the kilograms per cubic metre, the higher the volumetric weight of the same goods.
| Mode | Formula or factor | Equivalent kg per m³ | Notes |
|---|---|---|---|
| Air cargo (IATA standard) | cm³ ÷ 6,000 | ≈ 166.67 kg | Widely used by airlines and agents |
| Courier / express | cm³ ÷ 5,000 | 200 kg | Each company's own policy |
| Sea LCL (W/M) | 1 m³ = 1 revenue ton | 1,000 kg | Greater of m³ and tonnes |
| Road (truck) | per tariff | often 250–333 kg | Some charge per trip, per kg or per m³ |
Road factors vary most. Some Indonesian trucking companies quote a flat rate per trip, others per kilogram with a volume factor. Always check the carrier's rate card before comparing offers.
Worked example: air cargo
Shipment 1 — light goods. Three cartons of 60 × 50 × 40 cm, 12 kg each.
- Volume per carton: 60 × 50 × 40 = 120,000 cm³.
- Volumetric weight per carton: 120,000 ÷ 6,000 = 20 kg; 60 kg for three cartons.
- Total actual weight: 3 × 12 = 36 kg.
- Chargeable weight: 60 kg (volumetric is higher).
Sent by courier with a 5,000 divisor, the volumetric weight becomes 24 kg per carton, or 72 kg in total. The same goods are billed 12 kg heavier purely because of the divisor.
Shipment 2 — dense goods. Two 40 × 30 × 25 cm cartons of metal spare parts, 20 kg each. The volumetric weight is 30,000 ÷ 6,000 = 5 kg per carton, or 10 kg in total, while the actual weight is 40 kg. Chargeable weight is 40 kg (actual).
Shipment 3 — consolidated. If both shipments travel on one air waybill, the comparison covers the whole consignment: volumetric 60 + 10 = 70 kg, actual 36 + 40 = 76 kg. Chargeable weight is 76 kg, lower than billing them separately (60 + 40 = 100 kg). That is why forwarders like to combine light and dense cargo.
Rounding. Five cartons of 55 × 45 × 35 cm at 9.6 kg each: volumetric 5 × 86,625 ÷ 6,000 = 72.1875 kg, actual 48 kg. Rounded up to the next 0.5 kg, the chargeable weight is 72.5 kg. Try scenarios like this in the Chargeable Weight Calculator.
Worked example: sea LCL and road
At sea, LCL cargo is charged per W/M (weight or measurement): take the greater of volume in cubic metres and weight in metric tonnes.
| Shipment | Volume | Weight | W/M charged | Cost at a hypothetical USD 50/W/M |
|---|---|---|---|---|
| Garments | 4.2 m³ | 2,800 kg (2.8 t) | 4.2 | USD 210 |
| Ceramic tiles | 1.5 m³ | 3,200 kg (3.2 t) | 3.2 | USD 160 |
| Small samples | 0.4 m³ | 150 kg | 1.0 (minimum) | USD 50 |
The USD 50 rate is purely illustrative, not a market price. Many LCL tariffs also apply a 1 W/M minimum, as the last row shows. Volume comes from CBM; see how to calculate CBM for the formula and rounding, or use the CBM Calculator. When LCL stops making sense is covered in LCL vs FCL.
For road freight, take a 3 m³ shipment weighing 500 kg with a carrier that uses 250 kg per cubic metre. Its volumetric weight is 3 × 250 = 750 kg, so 750 kg is billed. At 333 kg per cubic metre the figure is 999 kg. For full loads a per-trip rate is usually more relevant; the fleet options are described in Indonesian truck sizes.
Shortcut: look at shipment density
You can predict which side wins without working through everything by looking at density: actual weight divided by volume (kg per m³). Below the mode factor you pay for volume; above it you pay for weight.
| Shipment | Density | Air (166.67 kg/m³) | Sea W/M (1,000 kg/m³) |
|---|---|---|---|
| Shipment 1 (light cartons) | 36 kg ÷ 0.36 m³ = 100 kg/m³ | Volume wins | Volume wins |
| Shipment 2 (spare parts) | 40 kg ÷ 0.06 m³ ≈ 667 kg/m³ | Weight wins | Volume wins |
| Garments LCL | 2,800 kg ÷ 4.2 m³ ≈ 667 kg/m³ | Weight wins | Volume wins |
| Ceramic tiles LCL | 3,200 kg ÷ 1.5 m³ ≈ 2,133 kg/m³ | Weight wins | Weight wins |
This is the mirror image of stowage factor, which is expressed in cubic metres per tonne. High-stowage-factor cargo "cubes out" first, while dense cargo "weighs out" first. Knowing density early helps you choose both mode and packaging.
Common mistakes
- Comparing carton by carton and adding the larger figures. Actual vs volumetric is compared for the whole shipment, not mixed per package.
- Measuring without the pallet. If goods travel on a pallet, measure the pallet and its load, including any overhang.
- Assuming every carrier uses 6,000. Couriers, certain airlines and domestic services may use other factors. Check the contract or the carrier's website.
- Ignoring rounding. A 59.6 cm side may be recorded as 60 cm by the warehouse, and weight is rounded up. Calculate with the numbers the carrier will use.
- Forgetting that packaging can shrink. A carton 3 cm too tall adds volumetric weight to every shipment. Right-sizing packaging is often cheaper than negotiating the rate.
How to reduce chargeable weight
Choose carton sizes that fit the product, combine dense and light goods in one consignment where possible, and move bulky light goods by sea when time allows, since 1,000 kg per cubic metre is far kinder to light cargo. For air pallets, also respect the height limits and ULD contours the airline sets.
Calculate before you book
Enter each package's dimensions and weight in the Chargeable Weight Calculator to compare air, courier and sea factors side by side. If the shipment is large enough for a truck or container, continue to the 3D load planner to see how the load stacks. Calculator results are estimates; the final invoice follows the carrier's own measuring, weighing and applicable tariff.