In short: The 6,000 divisor, where 167 kg per cbm comes from, checking the next rate break, and a full PVG to MEL quote.
Air freight is sold by the kilo, but not always by the kilo the cargo actually weighs. Light, bulky cargo takes up space on the aircraft that could have carried something heavier, so airlines charge on whichever is greater: the actual weight or a weight calculated from the volume. Getting this wrong is the commonest reason an air quote turns into an awkward invoice.
Volumetric weight in kilograms is length x width x height in centimetres, divided by 6,000. The chargeable weight is the higher of the gross weight and the volumetric weight (Maersk, air cargo chargeable weight). Maersk describes the 6,000 divisor as an industry standard set by IATA, and notes that some carriers use 5,000 instead. Express couriers commonly use 5,000, which makes the same box heavier on paper, so check which divisor applies before you quote.
In other words, 6,000 cubic centimetres counts as one kilo.
One cubic metre is 1,000,000 cm³. Divided by 6,000, that's 166.67 kg, which the industry rounds to 167. So the quick check is:
Put another way, cargo denser than 167 kg per cbm charges on actual weight; anything lighter charges on volume. Most consumer goods, apparel and furniture are lighter than that. Machine parts and printed matter often aren't.
Calculate volumetric weight from each piece's outside dimensions, including the pallet if it's palletised, and add them up. Use the longest point on each side. A carton listed as 60 x 50 x 40 cm on the packing list but bulging to 62 cm will be measured at 62 by the terminal.
Check how your airline or consolidator rounds dimensions and weights, and quote on the same basis. If the cargo is palletised and can't be stacked, ask whether it'll be charged on the pallet's full height or on a non-stackable basis, because that can change the chargeable weight a lot.
12 cartons, each 60 x 50 x 40 cm and 18 kg, Shanghai (PVG) to Melbourne (MEL).
Per carton: 60 x 50 x 40 = 120,000 cm3 / 6,000 = 20 kg volumetric Volumetric weight: 12 x 20 kg = 240 kg Gross weight: 12 x 18 kg = 216 kg Chargeable weight: greater of 240 and 216 = 240 kg Check by volume: 12 x 0.12 cbm = 1.44 cbm x 167 = 240.5 kg
The shipment charges on 240 kg, not 216. If you'd quoted on gross weight, you'd be 24 kg short on every per-kilo line: the freight rate and any surcharges the carrier charges per chargeable kilo.
Air rates are usually sold in weight breaks: a minimum charge, then a rate per kilo for under 45 kg, 45 kg and over, 100 kg and over, 300, 500 and 1,000 kg. The per-kilo rate falls as the weight rises. Because of that, it can be cheaper to charge a shipment as if it weighed the next break up.
Using example rates of A$6.20/kg at +100 and A$5.40/kg at +300:
240 kg at +100: 240 x 6.20 = AUD 1,488.00 Charged as 300 kg at +300: 300 x 5.40 = AUD 1,620.00 Lower: AUD 1,488.00, so charge at actual chargeable weight Now 280 kg: 280 kg at +100: 280 x 6.20 = AUD 1,736.00 Charged as 300 kg at +300: 300 x 5.40 = AUD 1,620.00 Lower: AUD 1,620.00, so charge as 300 kg
The crossover point here is 300 x 5.40 / 6.20, about 261 kg. Anything chargeable between 262 and 299 kg is cheaper billed at 300. Customers rarely check this; good forwarders do it automatically.
The 12-carton shipment above, airport to door in Melbourne metro, cleared, value A$12,500. Forwarder rates are examples, not a tariff. The government charges are the ABF import processing charge of $152 for an electronic declaration on a consignment of $10,000 or more (ABF) and the biosecurity full import declaration charge for air cargo of $48 from 1 July 2026 (DAFF, 2026–27 fees and charges).
Air freight PVG-MEL 240 kg x AUD 6.20 (+100) ............ AUD 1,488.00 Fuel and security surcharges 240 kg x AUD 1.10 ........... AUD 264.00 Destination terminal and handling, 240 kg ............... AUD 145.00 Customs clearance (brokerage) ............................ AUD 160.00 ABF import processing charge (at cost) ................... AUD 152.00 Biosecurity full import declaration, air (at cost) ........ AUD 48.00 Delivery 12 cartons, metro zone .......................... AUD 140.00 ------------------------------------------------------------------------- TOTAL .................................................. AUD 2,397.00 Priced on chargeable weight 240 kg (gross 216 kg, 1.44 cbm).
That last line is the one that saves arguments. Show gross weight, volume and chargeable weight on every air quote, so when the airline's figure comes back the customer can see where it came from.
At 1.44 cbm, the same cartons as LCL would charge on 1.44 W/M, because they weigh only 0.216 tonnes. If the customer can wait, quoting both is a service. The method for the sea side is in how to calculate an LCL quote, and which origin charges you include depends on the Incoterm (Incoterms 2020 for forwarders).
To check a shipment quickly, use the free freight calculator, then lay the quote out with the air freight quote template.
Laneworks reads dimensions and weights from the email or the attached packing list, works out chargeable weight, checks the next rate break, and drafts the reply from your rate sheet with the working shown. There's a sample draft on the site. Forward a real air request to try@getlaneworks.com and see one on yours in about two minutes.
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