If your air freight bill looks higher than the box’s actual weight justifies, chargeable weight is why. Air carriers sell space by volume as much as by mass, because a light, bulky carton wastes aircraft capacity the same way a heavy one does. Understanding this single rule is the fastest way to stop overpaying on China air freight.
The Rule That Decides Your Air Rate
You are billed on whichever is greater: the actual gross weight or the volumetric (chargeable) weight. A dense box of bolts bills on its real weight. A large box of pillows bills on its volume, because that volume occupies a seat on the plane whether it is heavy or not. The carrier picks the higher number — that is your chargeable weight.
How Volumetric Weight Is Calculated
The standard formula for general air cargo is:
Volumetric weight (kg) = Length × Width × Height (cm) ÷ 6000
Express couriers often use ÷5000, which produces a higher chargeable weight — about 20% more — for the same box. This is one reason express looks expensive beyond the base rate. Always confirm which divisor your quote uses.
Example: a carton 60 × 50 × 40 cm = 120,000 cm³. ÷6000 = 20 kg chargeable. If the box actually weighs 8 kg, you are billed for 20 kg.
A Worked Example
| Carton | Actual weight | Dimensions (cm) | Volumetric (÷6000) | Billed as |
|---|---|---|---|---|
| A (dense) | 25 kg | 40×30×25 | 5 kg | 25 kg (actual) |
| B (bulky) | 8 kg | 60×50×40 | 20 kg | 20 kg (volumetric) |
Carton B is where money leaks. The fix is rarely “ship less” — it is “pack smarter.”
Why Consolidation Shrinks Chargeable Weight
At the consolidation warehouse, several tricks cut volumetric weight before the plane is booked:
- Right-sizing cartons — replacing oversized boxes with snug ones removes dead air.
- Vacuum or compression packing — textiles and cushions lose 30%–50% of their volume.
- Stacking into master cartons — odd gaps between supplier boxes disappear when merged.
- Removing supplier packaging — double boxes from factories are a common, avoidable inflate.
These cuts apply across your whole batch, so the consolidated chargeable weight is almost always below the sum of the separate shipments. Pair this with a better weight-break tier and the saving compounds.
When Actual Weight Wins
If your goods are genuinely dense — metal parts, electronics, tiles — actual weight exceeds volumetric and packing tricks will not help much. In that case the lever to pull is the weight-break tier (ship more together to drop the per-kg rate) rather than volume reduction. Knowing which regime your product lives in tells you where to focus.
Practical Steps to Lower Your Chargeable Weight
- Measure every carton before booking; do not trust supplier estimates.
- Ask the warehouse to repack bulky items and drop ÷6000 vs ÷5000 clarity in writing.
- Consolidate multiple suppliers so master cartons replace individual boxes.
- For recurring orders, standardise carton sizes to minimise wasted space.
For the broader rate picture these weights feed into, our 2026 air rate guide shows how chargeable weight translates into the final per-kg number.
Frequently Asked Questions
What is the difference between actual and chargeable weight?
Actual weight is what the scale reads. Chargeable weight is the higher of actual weight and volumetric weight (dimensions ÷ 6000 for general cargo, ÷ 5000 for express). You are billed on chargeable weight.
Why does my light box get billed at a heavy weight?
Because of dimensional weight. A 60kg box at 120×80×90cm has a volumetric weight of 144kg, and carriers bill the greater number. Bulky-light cargo is the classic victim.
Does consolidation really lower chargeable weight?
Yes, in two ways: repacking removes dead space between parcels (smaller total volume), and moving from a 5000 divisor (couriers) to a 6000 divisor (consolidated general cargo) lowers the dimensional figure on every box.
Is volumetric weight the same for sea freight?
No. Sea freight typically uses 1 CBM = 1000kg as the threshold, a much gentler divisor, which is why very bulky goods often shift to ocean unless speed is critical.