Air freight quotes live and die on one number: chargeable weight — the greater of what your shipment weighs and what its volume "weighs" under the IATA convention. Master the two-line calculation and you can sanity-check any forwarder's quote in under a minute.
The convention
Chargeable weight = max(actual, volumetric)
6,000 cm³/kg assumes freight at 166.7 kg/m³ (10.4 lb/ft³). Express integrators sometimes apply the stricter 5,000 cm³/kg (200 kg/m³) — a quote's divisor is worth checking before you compare providers.
Worked examples
| Shipment | Volume | Volumetric | Actual | Chargeable |
|---|---|---|---|---|
| 10 cartons 40×40×40 cm, 8 kg each | 0.64 m³ | 106.7 kg | 80 kg | 106.7 kg |
| Pallet 120×100×120 cm, machine parts | 1.44 m³ | 240 kg | 410 kg | 410 kg |
| Pallet 48×40×48 in, foam goods 118 kg | 1.51 m³ | 252 kg | 118 kg | 252 kg |
Pattern: dense industrial freight pays actual weight; consumer goods, apparel and anything foam pays volumetric. The break-even density is exactly the divisor's assumption — above 166.7 kg/m³ actual wins, below it volume wins.
Cutting chargeable weight
Every centimeter compounds: shaving 5 cm off a 120 cm carton height cuts volumetric weight ~4%. Vacuum-pack soft goods, ship knocked-down instead of assembled, and consolidate cartons into fewer, fuller boxes. When volumetric weight still dominates after packing discipline, price ocean or LTL against air — modes that charge by density band (freight class) often flip the economics for light bulky freight.