How does Air Freight differ to sea freight ?

Air freight uses a volumetric weight calculation

In accordance with IATA (International Air Transport Association) volumetric standards, volumetric weight will apply if a shipment is below a certain weight density. The chargeable weight of airfreight is the higher of the actual gross weight or the volumetric weight. Volumetric weight: Height (cm) x Length (cm) x Depth (cm) 6,000. For example, the volumetric weight of a box of 40 x 60 x 50 cm will be 20. If the gross weight of this box is 25 kg, the chargeable weight is 25 kg (25 is larger than 20), however if the weight of this box is only 1 kg, then the chargeable weight will be 20 kg (20 is larger than 1). Volumetric weight is likely to apply when shipping objects low in weight density such as duvets, guitars or bicycles.