Chargeable weight is the weight the carrier actually bills you — it is the higher of your shipment's actual (gross) weight or its volumetric (dimensional) weight. Because carriers sell space, not just payload capacity, a large light package occupies the same amount of aircraft hold space as a small heavy one. The formula for volumetric weight in air freight is: L(cm) × W(cm) × H(cm) ÷ 6,000 = volumetric weight in kg. If that figure is higher than your actual weight, you pay for the volumetric weight.
What Is Chargeable Weight?
Every air freight carrier — and most courier services — bills on chargeable weight, not gross weight. The concept is straightforward: aircraft hold space is finite. A large box filled with feathers takes up just as much room as a small box of lead. To compensate for space-inefficient cargo, carriers apply a volumetric (dimensional) weight formula and charge whichever is higher.
This is why your air freight invoice sometimes shows a weight that seems impossibly high compared to what you loaded onto the truck. The carrier isn't making an error — it is applying industry-standard chargeable weight rules.
The Volumetric Weight Formula — Why Light Bulky Cargo Costs More
The international standard formula for air freight volumetric weight (set by IATA) is:
Volumetric Weight (kg) = L(cm) × W(cm) × H(cm) ÷ 6,000
This means that 6,000 cm³ of volume is treated as equivalent to 1 kg of actual weight.
Worked Example
You're shipping a single box measuring 50 × 40 × 30 cm with an actual weight of 2 kg.
- Volumetric weight: 50 × 40 × 30 ÷ 6,000 = 10 kg
- Actual weight: 2 kg
- Chargeable weight: 10 kg (volumetric wins)
- At a rate of $8/kg: you pay $80, not $16
A first-time shipper almost always budgets based on gross weight and gets an invoice 3–5× higher than expected.
The Three Divisors You Need to Know
The divisor changes depending on the mode of transport and the carrier type. Knowing which divisor applies to your shipment prevents miscalculation:
| Mode / Carrier | Divisor | Equivalent | Notes |
|---|---|---|---|
| Air Freight (IATA standard) | 6,000 | 1 CBM = 167 kg | Used by airlines and most air freight forwarders |
| International Courier (DHL, FedEx, UPS) | 5,000 | 1 CBM = 200 kg | More aggressive — courier parcels are priced higher |
| Ocean LCL (W/M billing) | 1,000 (per tonne) | 1 CBM = 1,000 kg | Charged per revenue ton — higher of 1 tonne or 1 CBM |
| Road Freight (Europe) | 3,000 | 1 CBM = 333 kg | Varies by carrier; some use 4,000 |
Always confirm the divisor with your specific carrier before budgeting. Some niche air cargo operators use 6,000 for heavy-lift cargo but 5,000 for express services.
Real-World Example: An FBA Seller's Air Freight Shock
Here is a scenario that plays out thousands of times every month on Amazon FBA shipments from Asia:
A seller is launching a line of decorative throw pillows. Factory specifications:
- 100 units, each packed in its own carton measuring 40 × 30 × 20 cm
- Gross weight per carton: 300 g (0.3 kg)
- Total actual weight: 100 × 0.3 kg = 30 kg
The seller gets an air freight quote at $4 per kg and budgets $120 for freight.
Then the invoice arrives:
- Volumetric weight per carton: 40 × 30 × 20 ÷ 6,000 = 4 kg
- Total volumetric weight: 100 × 4 kg = 400 kg
- Chargeable weight: 400 kg (volumetric, not actual, wins)
- Invoice: 400 kg × $4 = $1,600
The seller receives a bill of $1,600 against a budget of $120. The freight cost now exceeds the product cost. This is not unusual for soft goods, foam, plastic components, or any cargo with a density below 167 kg/m³.
The density threshold for air freight is 167 kg/m³ (1 CBM ÷ 6,000 divisor = 0.167 kg/litre). If your cargo is less dense than that, volumetric weight will always win.
How to Reduce Your Chargeable Weight
Once you understand the mechanism, there are several practical ways to reduce your chargeable weight and therefore your freight bill:
- Tighter packaging: Reduce dead air inside cartons. A pillow in a 40×30×20 cm box versus a 32×24×16 cm box reduces volumetric weight by nearly 50% — even if the actual weight is the same.
- Vacuum packing for soft goods: Pillows, garments, stuffed toys, and foam products can be compressed dramatically. A pillow compressed from 40×30×20 cm to 30×20×10 cm reduces volumetric weight by 75%.
- Master carton consolidation: Instead of 100 individual cartons, pack 10 units per master carton. The master carton ratio (internal volume ÷ actual volume of goods) is far more efficient.
- Repackage at origin: Work with your freight forwarder or a China-based 3PL to repack goods before export. This service typically costs $0.30–$1.50 per unit and often saves 3–5× that in freight.
- Compare sea vs air: If your chargeable weight is extremely high due to bulky light cargo, ocean freight with a 5–7 day transit may be more economical. Use our chargeable weight tool to compare the two modes side by side.
Frequently Asked Questions
What is the chargeable weight divisor for DHL express?
DHL Express uses a divisor of 5,000, meaning 1 CBM = 200 kg volumetric weight. This is more aggressive than the IATA standard of 6,000 used by airlines and air freight forwarders. FedEx and UPS also use 5,000 for international express parcels.
How do I calculate chargeable weight for multiple boxes?
Calculate the total actual weight (sum of all box weights) and the total volumetric weight (sum of all volumetric weights calculated individually). Chargeable weight = the higher of the two totals.
Does chargeable weight apply to ocean freight?
Yes, but the mechanism is different. Ocean LCL uses W/M billing — you pay per revenue ton, which equals either 1 metric tonne or 1 CBM, whichever is greater. The equivalent "divisor" is 1,000.
Can I negotiate the divisor with my carrier?
For large volumes, yes. Some airlines and freight forwarders will negotiate a 6,000 divisor for heavy cargo that consistently runs above 167 kg/m³. For express courier parcels, the divisor is generally fixed at 5,000 and non-negotiable.
What is the "break-even density" for air freight?
The break-even density for air freight at the 6,000 divisor is 167 kg/m³. If your cargo is denser than 167 kg/m³, actual weight wins and you pay for gross weight. If your cargo is lighter than 167 kg/m³, volumetric weight wins. For courier shipments at the 5,000 divisor, the break-even density is 200 kg/m³.
Stop guessing what your carrier will charge you. Enter your box dimensions and actual weight into our calculator and see the chargeable weight instantly. Calculate your chargeable weight before your carrier does →