IATA Volumetric Weight Formula for Air Freight
The IATA 6000 cm3/kg divisor explained, worked examples for general cargo and express, and how carriers actually apply the higher of gross vs volumetric weight when they price a shipment.
Air freight is priced on the higher of gross weight and volumetric weight, and volumetric weight always uses the IATA 6000 cm3/kg divisor. That single formula decides whether a shipment ships as "1000 kg" or "3500 kg" chargeable - a 3.5x difference on the same box. This guide covers the formula, the carrier-specific divisors that trip up first-time shippers, and worked examples for the shipment sizes you see every week.
The formula
Volumetric weight (kg) = L × W × H (cm) ÷ 6000
The 6000 divisor is the IATA standard for general air cargo under TACT Rule 3.9.1. Express integrators use 5000 cm3/kg on domestic services and 6000 cm3/kg on international. Confirm the divisor on the specific carrier's tariff before pricing.
Worked examples
- Single pallet (120 × 80 × 100 cm), 250 kg gross - volumetric = 120 × 80 × 100 / 6000 = 160 kg. Chargeable weight = max(250, 160) = 250 kg. Gross wins.
- Same pallet with foam packaging, 60 kg gross - volumetric still 160 kg. Chargeable = 160 kg. Volumetric wins - shipper pays 2.7× the gross weight.
- Express parcel (40 × 30 × 20 cm), 3 kg gross - volumetric = 40 × 30 × 20 / 5000 = 4.8 kg on domestic. Chargeable = 4.8 kg. Rounded up to next 0.5 kg = 5 kg.
Why the divisor is 6000
A cubic metre of hold space converts to 1,000,000 cm3. Divide by 6000 and you get 166.7 kg per CBM - the maximum practical density an aircraft can carry without breaching weight-and- balance limits. Anything lighter than that is paying for hold space rather than weight capacity, so the carrier charges by volume. Sea freight uses a different equivalence (1 CBM = 1000 kg = 1 tonne) because ships are volume-limited, not weight-limited.
How to calculate for irregular loads
Use the bounding-box method: measure the smallest rectangular box that fully contains the shipment. For pallets, include the pallet itself. For projecting fittings or handles, include the projection. Some carriers add a 5 to 10 percent build-up allowance on top of the bounding box - check the airway bill tariff or ask before booking.
Metric vs imperial
Same physics, different numbers. In inches and pounds:
Volumetric weight (lb) = L × W × H (inches) ÷ 366
366 in3/lb is the exact imperial equivalent of 6000 cm3/kg. Never mix units in one calculation - convert all three dimensions to the same system before dividing.
Model your shipment
Run the numbers through the Air Freight Calculator - it handles metric or imperial input, applies the correct divisor for general vs express, and returns chargeable weight and an indicative rate. For sea cargo the same load logic runs through the CBM Calculator.
Frequently asked questions
What is the IATA volumetric weight formula?#
Volumetric weight (kg) = Length (cm) × Width (cm) × Height (cm) ÷ 6000. IATA uses a 6000 cm3/kg divisor for general air cargo, which means 1 kg of chargeable capacity is equivalent to 6000 cubic centimetres of hold space. Express integrators (FedEx, DHL, UPS) use 5000 cm3/kg on domestic and 6000 cm3/kg on international, so check the specific carrier's tariff.
How is the chargeable weight determined?#
The carrier compares the actual gross weight against the volumetric weight and charges on the higher of the two. On dense cargo (metal parts, batteries, liquids) actual weight usually wins. On low-density cargo (garments, furniture, foam packaging) volumetric weight almost always wins. Bill of lading always shows both figures and the chargeable weight applied.
Why is the divisor 6000 for air and different for other modes?#
The 6000 cm3/kg divisor represents the maximum useful density of an aircraft hold given weight-and-balance constraints. Sea freight has effectively unlimited weight capacity per container, so ocean uses 1000 cm3/kg for volumetric weight calculation - which is the CBM basis (1 CBM = 1000 kg of chargeable equivalent). Road freight sits between at 3000 or 4000 cm3/kg depending on the market.
How do I convert between metric and imperial?#
The metric formula (L × W × H in cm / 6000) gives kg. The imperial equivalent is L × W × H in inches / 366, which gives pounds. Both use the same 6000 cm3/kg density. Never mix units - if any dimension is quoted in inches, convert all three before dividing.
What happens with pallets and irregular shapes?#
Carriers measure the smallest rectangular box that contains the shipment (the bounding box), including any overhang. Pallet dimensions include the pallet itself. For irregular items, most carriers apply a build-up allowance of 5 to 10 percent on top of the bounding-box calculation to reflect handling constraints.