You weighed the shipment at 62 kilograms, the quote came back priced on 100, and nothing in between was explained. This is the most common surprise in air freight and it is not an error — it is how the industry has priced cargo for decades.
The formula behind it takes two minutes to understand. What takes longer, and what almost nobody publishes, is the part that actually matters: the three levers that let you change the number once you know how it was calculated.
Air freight is charged on whichever is greater: the actual gross weight, or the volumetric weight calculated as length × width × height in centimetres divided by 6,000. If your cargo is light relative to its size, you pay on volume. The threshold is 167 kilograms per cubic metre — below that density, volume decides your bill.
Three steps, in order.
First, weigh the shipment. That is your actual gross weight, including all packaging.
Second, calculate volumetric weight. Multiply length × width × height in centimetres for each package, add them together, and divide the total by 6,000.
Third, compare the two. The higher number is your chargeable weight, and it is what the rate is applied to.
Five cartons, each measuring 60 × 50 × 40 cm, weighing 62 kg in total.
Volume per carton: 60 × 50 × 40 = 120,000 cm³
Total volume: 120,000 × 5 = 600,000 cm³
Volumetric weight: 600,000 ÷ 6,000 = 100 kg
Actual weight is 62 kg. Volumetric weight is 100 kg. You are charged on 100 kg — a 61% increase over what the scale said, and the entire explanation for a quote that looked wrong.
Volumetric weight — also called dimensional weight or chargeable volume — is a way of pricing the space a shipment occupies rather than its mass.
An aircraft runs out of space long before it runs out of lift. A hold filled with pillows reaches its volume limit at a fraction of its weight limit, and if carriers charged that shipment by the scale they would fly a full aircraft for almost no revenue. Volumetric weight converts cubic space into a billable equivalent so that light, bulky cargo pays for the room it takes.
The same logic applies to sea freight, where it appears as the W/M rule, and to express couriers, who use a different divisor.
The 6,000 divisor is the IATA standard for air cargo, and it encodes a density assumption: one cubic metre of space is treated as equivalent to 167 kilograms.
A cubic metre is 1,000,000 cm³. Divided by 6,000, that gives 167 kg. So any cargo denser than 167 kg per cubic metre is charged on its actual weight, and anything lighter is charged on volume.
Express couriers — DHL, FedEx, UPS, TNT — use 5,000 instead, which works out to 200 kg per cubic metre. Same shipment, different divisor, higher bill.
| Service | Divisor | Equivalent density | 600,000 cm³ becomes |
|---|---|---|---|
| Air freight (IATA standard) | ÷ 6,000 | 167 kg/m³ | 100 kg |
| Express courier | ÷ 5,000 | 200 kg/m³ | 120 kg |
| Sea freight LCL | W/M rule | 1,000 kg/m³ | 0.6 units |
Now that you can calculate the number, here is what almost nobody explains: three separate mechanisms can push your bill above what a simple volumetric calculation predicts.
Most air freight rates carry a minimum charge, commonly set around 45 kilograms. Below that threshold you pay the minimum regardless of how small the shipment is.
A 12 kg consignment and a 45 kg consignment frequently cost the same. This is why small air freight shipments price so poorly against express couriers, and why the honest advice below about 45 kg is usually to use a courier instead.
Air freight rates are not a flat price per kilo. They step down at weight thresholds, typically at 45, 100, 300, 500 and 1,000 kilograms, and the rate at each break applies to the whole shipment.
That creates a situation that surprises most shippers the first time they see it.
Take a shipment with a chargeable weight of 95 kg. At the +45 kg rate of, say, $6.50 per kilo, that is 95 × 6.50 = $617.50. But at the +100 kg rate of $5.80 per kilo, a 100 kg shipment costs 100 × 5.80 = $580.
Declaring 100 kilos is $37.50 cheaper than declaring 95. You pay for five kilos you are not shipping and save money doing it.
Any competent forwarder applies the lower of the two automatically — it is standard practice, not a trick. But if you are sitting just below a break at 92 kg, 280 kg or 940 kg, it is worth asking whether adding a little more cargo is effectively free. Sometimes the next carton costs nothing to ship.
Chargeable weight is normally rounded up to the nearest half kilogram, and on some carriers to the nearest full kilogram. On a small shipment this is negligible. On a consignment with many individually rated pieces it accumulates.
Often, yes — sometimes dramatically. But one of the standard pieces of advice can make things considerably worse, so take these in order.
The cheapest win is the empty air inside your cartons. A product occupying 60% of its box means you are paying to fly 40% nothing.
Right-size the carton to the product, replace bulky void fill with thinner protective material where the cargo allows, and nest or disassemble anything that can safely travel that way. On a light, bulky shipment a packaging review of an afternoon frequently takes 15–25% off the chargeable weight, which repeats on every shipment thereafter.
Palletising is the default advice for air freight, and on small shipments it can double your bill.
Eight cartons, each 40 × 40 × 40 cm, weighing 70 kg in total.
Shipped loose: volume is 64,000 cm³ per carton × 8 = 512,000 cm³. Volumetric weight is 512,000 ÷ 6,000 = 85.3 kg. Chargeable weight: 85.3 kg.
Palletised on a standard 120 × 100 cm pallet: those cartons fit six to a layer, so eight cartons means two layers — 80 cm of cargo, plus roughly 15 cm for the pallet itself, giving 95 cm of height. The billed dimensions become 120 × 100 × 95 = 1,140,000 cm³. Volumetric weight is 190 kg.
The cargo did not change. The chargeable weight more than doubled, because you are now paying for the empty corners of a pallet footprint your cargo does not fill.
The rule: palletise when you have enough cartons to fill the footprint efficiently, or when the cargo genuinely needs the protection. Do not palletise a small loose shipment out of habit. Ask your forwarder to price it both ways — we do this routinely and the difference regularly surprises people.
If you are shipping from several suppliers, or shipping weekly when fortnightly would do, consolidation moves you down the rate-break table.
Four separate 60 kg shipments each pay the +45 kg rate. One 240 kg consolidated shipment pays the +100 kg rate, and possibly reaches +300 with a little more volume. The saving is frequently larger than anything you achieve through repacking, and it comes with fewer documentation sets and fewer clearance events.
Express couriers run a single integrated network. One company collects from your supplier, flies it, clears it and delivers to your door, on one price per kilo with everything bundled.
Air freight uses scheduled cargo capacity on commercial aircraft. It is quoted airport to airport, and pickup, customs clearance and final delivery are arranged separately — by your forwarder, but priced as distinct lines.
The consequence is that express carries high fixed convenience and low incremental cost, while air freight carries low fixed cost and much better economics as weight grows.
| Chargeable weight | Usually better | Why |
|---|---|---|
| Under 45 kg | Express | Air freight minimums and fixed handling make small shipments uneconomic |
| 45–100 kg | Depends — price both | Express convenience may still justify the premium |
| 100–300 kg | Air freight, usually | Rate breaks start to bite, express pricing stays roughly linear |
| Over 300 kg | Air freight, decisively | The gap widens with every break, and express surcharges compound |
Airport to airport on the main China–Europe lanes, two to five days depending on whether the routing is direct or transhipped.
Add one to two days at origin for pickup, security screening, build-up onto ULDs and export clearance. Add one to three days at destination for customs and final delivery. Door to door, a realistic window is five to nine days.
Express is faster and more predictable — typically three to five days door to door — because the network is integrated and the handovers are internal. If your deadline is inside four days, express or a charter are the honest answers, not scheduled air freight.
For cargo that genuinely cannot wait for the next available scheduled space — an aircraft on ground, a production line stopped — charter removes the capacity risk entirely.
A comparable quote should itemise:
At origin — pickup from your supplier, security screening, terminal handling, export customs declaration and documentation.
On the air leg — base air freight on the chargeable weight, plus fuel and security surcharges. These are quoted separately and are not trivial.
At destination — terminal handling, customs clearance, and delivery to your address.
Usually separate, and worth confirming rather than assuming: duties and import VAT, storage beyond the free period, inspection fees if the shipment is selected, and cargo insurance.
If a quote arrives as a single number per kilo, ask what is inside it before comparing. Two quotes that look 20% apart frequently are not, once you find the surcharges one of them left out.
There is a point where repacking stops helping, and recognising it early saves more than any packaging review.
If your cargo is under about 100 kg per cubic metre — genuinely light and bulky — you will always be paying volumetric rates by air, and no amount of repacking changes the fundamental economics. At that density, the question is not how to make air freight cheaper. It is whether air freight is the right mode at all.
For China to Europe, rail sits between the two: roughly half the sea transit time at a small fraction of the air rate, and priced on container space rather than volumetric weight. For cargo that is too bulky for economical air and too urgent for a 35-day vessel, it is frequently the answer nobody asked about.
Send us the dimensions and weight and we will tell you which mode the numbers actually favour — including when that is not the one you asked us to quote.
Six things, and the first quote will be the real one.
The dimensions of each package in centimetres, measured packed rather than as the bare product. The gross weight of each package. The number and type of packages. The commodity description, and the HS code if you have one. The origin airport or supplier city, and the destination airport or full delivery address. And your required arrival date, with a note on whether it is firm.
We will come back with the chargeable weight calculated, the rate break it falls into, whether a small volume increase would drop you into a cheaper one, and a comparison against express and sea where either is worth considering.
Compare actual gross weight against volumetric weight — length × width × height in centimetres, divided by 6,000 — and the higher figure is charged. For a 600,000 cm³ shipment, volumetric weight is 100 kg; if the scale says 62 kg, you are billed on 100.
A billable equivalent for the space a shipment occupies rather than its mass. Aircraft run out of room before they run out of lift, so light bulky cargo is charged on volume to reflect the space it uses.
It is the IATA standard for air cargo and encodes an assumed density of 167 kg per cubic metre. Cargo denser than that is charged on actual weight; anything lighter is charged on volume.
Almost always volumetric weight exceeding actual weight. Three other mechanisms can add to it: a minimum charge around 45 kg, rate breaks applied at the wrong threshold, and rounding up to the nearest half kilo.
Above roughly 100 kg chargeable weight, usually yes, and the gap widens with weight. Below 45 kg express is normally cheaper as well as simpler, because air freight minimums and fixed handling do not scale down.
The crossover typically sits between 45 and 100 kg. Bulky cargo shifts it lower because express uses the 5,000 divisor and penalises volume harder.
Two to five days airport to airport on China–Europe lanes, plus one to two days at origin and one to three at destination — a realistic door-to-door window of five to nine days. Express is typically three to five.
Origin pickup, screening, terminal handling and export declaration; the air leg with fuel and security surcharges; destination handling, clearance and delivery. Duties, VAT, storage and insurance are usually separate — confirm rather than assume.
Often by 15–25% through eliminating void space. But palletising a small loose shipment can more than double the chargeable weight by adding the pallet footprint and height — ask for it priced both ways.
Express is one integrated door-to-door network at a bundled price per kilo. Air freight uses scheduled cargo capacity, is quoted airport to airport, and has pickup, clearance and delivery arranged separately. Express wins on simplicity and small consignments; air freight wins on weight.
