Guide
How to Calculate Chargeable Weight for Air & Courier
Air freight is billed on chargeable weight, not just actual weight. Learn how volumetric weight works, the formulas couriers use, and how to lower your bill.
A common surprise for new shippers: a light but bulky air shipment can cost far more than its scales suggest. That is because airlines and couriers charge on chargeable weight — the greater of actual weight and volumetric (dimensional) weight. Here is how it works and how to keep it down.
Why volumetric weight exists
Aircraft and vans run out of space before they run out of weight allowance. A box of pillows weighs little but fills a lot of cargo space that cannot then be sold to anyone else. To price fairly, carriers convert volume into a notional weight and bill whichever is higher. The principle is simple: you pay for the room your cargo occupies, not just its mass.
The formulas
Air freight (IATA standard):
Volumetric weight (kg) = Length × Width × Height (cm) ÷ 6000
Express couriers often use a denser divisor:
Volumetric weight (kg) = L × W × H (cm) ÷ 5000
The chargeable weight is then the larger of the volumetric weight and the actual gross weight, usually rounded up to the next 0.5 kg.
A worked example
Say you ship a carton measuring 60 × 40 × 50 cm and weighing 12 kg.
- Volume = 60 × 40 × 50 = 120,000 cm³
- Air volumetric weight = 120,000 ÷ 6000 = 20 kg
- Actual weight = 12 kg
The chargeable weight is 20 kg, not 12 — because the box takes up the space of a 20 kg shipment. With the courier divisor of 5000, it would be 24 kg.
How to lower your chargeable weight
- Right-size the packaging. Oversized boxes with lots of void space inflate volumetric weight. Use a carton that fits the goods.
- Reduce void fill. Swap bulky foam for tighter protective packing where it is safe to do so.
- Consolidate smartly. Combining several small parcels into one well-packed carton often reduces total dimensional weight.
- Consider the mode. If a shipment is consistently penalised on volume, sea or rail may be far cheaper for non-urgent goods.
The bottom line
Before you book air or courier, measure and calculate. If volumetric weight is much higher than actual weight, your packaging is probably costing you money. A tighter box or a different mode can cut the bill significantly — and a forwarder can tell you instantly which option wins for your dimensions.