Aviation numbers
Chargeable weight, and the divisor behind it.
You are billed on the greater of what the box weighs and what it occupies. The second figure depends on a number the carrier chooses — which is why the same box can cost two different amounts.
- 6000The IATA air-freight divisor. One cubic metre is deemed to weigh 167 kg.
- 5000What DHL, FedEx and UPS apply to international shipments — 200 kg to the cubic metre.
- The greater of the twoYou are billed on actual weight or volumetric weight, whichever is larger, rounded up.
The rule in one line
An aircraft runs out of space long before it runs out of lifting capacity. A hold filled with pillows would earn almost nothing if it were billed by weight alone, so carriers bill the greater of two numbers: what the shipment actually weighs, and what its volume is deemed to weigh.
Volumetric weight = length × width × height ÷ divisor, in centimetres and kilograms.
Chargeable weight = the greater of actual weight and volumetric weight, rounded up.
The divisor is a commercial term, not a constant
This is the part that surprises people. The divisor is not physics — it is a number in a contract, and different parts of the industry use different ones.
| Where | Divisor | 1 m³ is deemed to weigh |
|---|---|---|
| Air freight, IATA recommendation | 6000 | 167 kg |
| DHL, FedEx, UPS — international, cm | 5000 | 200 kg |
The lower the divisor, the heavier your box is deemed to be. A 60 × 40 × 40 cm carton is 16 kg volumetric at 6000 and 19.2 kg at 5000 — the same cardboard, a fifth more freight. If a quote does not state its divisor, that is the first question to ask.
6000 is the IATA industry tariff. DHL, FedEx and UPS all apply 5000 to international shipments measured in centimetres, so 5000 is the one that applies to a parcel leaving Türkiye with us.
The divisor is also a density in disguise, which is what makes it feel less like a trick. One cubic metre divided by 6000 is 166.7 kg, so 167 kg/m³ is the line: pack denser than that and you pay for the mass, lighter and you pay for the space. At a divisor of 5000 the line moves to 200 kg/m³.
Rounding, and why the fraction disappears
Carriers do not bill fractions. The chargeable figure is rounded up, normally to the next half kilogram, so 19.1 kg is invoiced as 19.5 kg. On a single carton that is noise; across a hundred pieces a month it is not.
Girth, and the fees no divisor predicts
Volume is not the only shape penalty. Networks are built around conveyors and roller beds, and a package that cannot ride one is handled by hand. The usual trigger is girth — the two shortest sides counted twice, plus the longest:
Girth = (2 × shortest side) + (2 × second shortest side) + longest side.
A long, thin item can pass every weight test and still attract an oversize fee on girth alone. The calculator above flags the two common thresholds so the fee appears before the shipment does, rather than on the invoice afterwards.
What this does not tell you
- It is a weight, not a price. What that weight costs depends on the lane, the service and the tariff in force.
- Duty and import VAT sit outside it entirely — they follow the value and the commodity code of the goods, not the size of the box.
- Dangerous goods, temperature control and lithium batteries change how a shipment moves regardless of what it weighs.
Sources: IATA volumetric weight practice for air cargo (divisor 6000); published express-carrier terms, which commonly apply 5000. Divisors and oversize thresholds are contractual and change — always confirm the figure on your own quotation.