In air freight, the chargeable weight is the greater of the shipment's gross weight and its volumetric weight. For general cargo, volumetric weight is length × width × height in centimetres divided by 6,000, which corresponds to roughly 167 kilograms per cubic metre. The result is usually rounded up to the next half kilogram.
Why are two different weights calculated?
An aircraft's cargo capacity is limited by both weight and volume. A box filled with foam weighs little but takes up a lot of space in the hold. To be paid for that space, the airline converts volume into a weight value. Under IATA rules the ratio accepted for general cargo is that 6,000 cubic centimetres count as 1 kilogram. Cargo lighter than roughly 167 kilograms per cubic metre is charged by volume, denser cargo by actual weight.
Calculation step by step
- Measure: Take the length, width and height of each piece in centimetres, including the pallet and at the outermost points.
- Find the volume: Multiply the three dimensions, multiply by the number of pieces and add up.
- Convert to volumetric weight: Divide the total cubic centimetres by 6,000.
- Compare: Take the greater of the total gross weight and the volumetric weight.
- Round: Round the result according to the carrier's rule, usually up to the next half kilogram.
Example calculations
| Shipment | Gross weight | Volumetric weight | Chargeable |
|---|---|---|---|
| 10 cartons, each 60×40×40 cm and 12 kg | 120 kg | 960,000 / 6,000 = 160 kg | 160 kg |
| Machine part crate, 120×80×70 cm | 350 kg | 672,000 / 6,000 = 112 kg | 350 kg |
| Pallet, 120×100×150 cm | 210.4 kg | 1,800,000 / 6,000 = 300 kg | 300 kg |
| Single carton, 50×50×50 cm | 18.2 kg | 125,000 / 6,000 = 20.833 kg | 21 kg |
In the first example the density of the cartons is about 125 kg per cubic metre; because it is below the 167 kg threshold, the charge is based on volume. The crate, on the other hand, is dense cargo and is charged on its actual weight.
Rounding, weight breaks and minimum charge
In practice volumetric weight is first calculated with decimals and then rounded; in countries using kilograms the common rule is up to the next half kilogram. Some carriers and express companies round to the full kilogram. Freight tariffs are structured in weight breaks; the higher the break, the lower the price per kilogram. So for a shipment just below a break, the total calculated at the minimum weight of the next break may turn out cheaper; the agent makes this comparison. For very small shipments a minimum charge applies. How to read quotes from this angle is covered in the entry comparing freight quotes.
Difference for courier and express shipments
Express and courier companies usually use a divisor of 5,000. The same 60×40×40 cm carton counts as 16 kg with the 6,000 divisor and 19.2 kg with the 5,000 divisor. For light and bulky products this difference goes straight onto the invoice; always ask which divisor applies when requesting a quote.
Reducing chargeable weight through packaging
- Reduce empty space inside the box; choose cartons sized to the product.
- Keep the top of the pallet flat and square; overhanging cartons increase the dimensions.
- Use stackable packaging; cargo marked non-stackable may be charged extra volume.
- Choose the pallet type to suit the cargo; the differences are in the entry Euro and industrial pallets.
- For large shipments, check in advance that the cargo fits the ULD contours.
Common mistakes
- Not including the pallet height in the dimensions
- Mixing up inches and centimetres
- Measuring irregularly shaped cargo by its body rather than its outermost points
- Applying the ocean freight W/M calculation to air freight
The chargeable weight is shown in a separate field on the AWB. For an accurate air freight quote, the gross weight and dimensions must be given separately for each piece.