Volumetric weight for air freight is calculated by multiplying the length, width, and height of your shipment (in centimeters), then dividing by 6,000. The result is expressed in kilograms. If your shipment’s volumetric weight is higher than its actual weight on a scale, the volumetric figure becomes the one you’re billed on.
The Standard Formula
The International Air Transport Association (IATA) sets the standard divisor for air cargo at 6,000 when you measure in centimeters and want the result in kilograms:
Volumetric Weight (kg) = Length (cm) × Width (cm) × Height (cm) ÷ 6,000
If you’re working in inches and pounds, the equivalent formula uses a divisor of 366:
Volumetric Weight (lbs) = Length (in) × Width (in) × Height (in) ÷ 366
Say you have a carton that measures 60 cm long, 40 cm wide, and 50 cm tall. Multiply those together to get 120,000 cubic centimeters, then divide by 6,000. The volumetric weight is 20 kg. If the box actually weighs 12 kg on a scale, the carrier charges you based on 20 kg because it’s the higher number. That 12 kg box is taking up the space of a 20 kg package, and the airline needs to account for the cargo hold space it occupies.
Why Carriers Use Two Divisors
You may encounter a divisor of 5,000 instead of 6,000 depending on the carrier or service. DHL, for example, uses 5,000 for its express and courier services (with dimensions in centimeters and weight in kilograms). The imperial equivalent for that divisor is 139 when measuring in inches and pounds. A divisor of 5,000 produces a higher volumetric weight than 6,000 for the same box, which means you’ll be billed more for bulky, lightweight shipments.
The 6,000 divisor is the IATA standard widely used for general air cargo booked through freight forwarders. The 5,000 divisor is more common with express parcel carriers and integrators. Always confirm which divisor your carrier or forwarder applies before quoting a shipment, because the difference can be significant. That same 120,000 cubic centimeter carton comes out to 20 kg with the 6,000 divisor but 24 kg with the 5,000 divisor.
How to Measure Your Shipment
Measure the longest point on each side of the package, not the interior dimensions. If a box bulges or has an irregular shape, use the farthest points as your length, width, and height. For palletized freight, measure the full footprint of the pallet including any overhang, and measure height from the pallet base to the tallest point of the cargo, including the pallet itself.
Round each measurement up to the nearest whole centimeter (or inch). Carriers do not round down, and even a fraction of a centimeter can push you into a higher volumetric weight bracket on large shipments. If you have multiple packages in one shipment, calculate the volumetric weight of each piece individually, then add them together for the total.
Chargeable Weight: Which Number You Actually Pay
Carriers compare two numbers for every shipment: the actual gross weight (what the shipment weighs on a scale) and the volumetric weight (what the formula produces). Whichever is higher becomes the “chargeable weight,” and that is the figure used to calculate your freight rate.
This system exists because aircraft have two constraints: how much weight they can carry and how much physical space the cargo hold offers. A shipment of pillows might weigh very little but fill an enormous amount of space. A shipment of machine parts might be heavy but compact. The chargeable weight rule ensures the carrier is compensated for whichever resource your shipment consumes more of.
Here’s a quick example comparing two shipments:
- Shipment A: A crate measuring 100 × 80 × 60 cm. Volume is 480,000 cm³. Volumetric weight is 480,000 ÷ 6,000 = 80 kg. Actual weight is 50 kg. Chargeable weight: 80 kg (volumetric wins).
- Shipment B: A crate measuring 40 × 30 × 30 cm. Volume is 36,000 cm³. Volumetric weight is 36,000 ÷ 6,000 = 6 kg. Actual weight is 25 kg. Chargeable weight: 25 kg (actual weight wins).
Reducing Your Volumetric Weight
Since volumetric weight is purely a function of the outer dimensions of your package, the most direct way to reduce it is to use smaller packaging. Eliminate excess void fill, choose boxes that fit the contents snugly, and avoid oversized cartons for small items. Even shaving a few centimeters off each dimension compounds quickly. Dropping a box from 60 × 40 × 50 cm to 55 × 35 × 45 cm cuts the volumetric weight from 20 kg to roughly 14.4 kg.
For palletized cargo, stack cartons to maximize the pallet footprint without overhang, and build as high as the airline or unit load device (the container that fits inside the aircraft) allows. Wasted vertical space on a pallet still counts in your height measurement. If you’re shipping multiple small packages, consolidating them into fewer, more efficiently packed cartons can lower total volumetric weight compared to sending each one individually.
Quick Reference for Common Divisors
- IATA standard (general air cargo): 6,000 (cm/kg) or 366 (in/lbs)
- Express carriers (common for parcel services): 5,000 (cm/kg) or 139 (in/lbs)
When you receive a freight quote, ask which divisor is being applied. Run the calculation yourself to verify the chargeable weight matches what appears on your rate sheet. Errors in dimension recording are common, and catching a measurement mistake before the shipment moves is far easier than disputing an invoice after delivery.