CBM & Chargeable Weight Explained: How Freight Is Priced

Almost every freight surprise on an invoice traces back to one misunderstood concept: chargeable weight. Carriers don't simply bill by how heavy your cargo is — they bill by whichever is greater, the actual weight or the space it takes up. Understand the two formulas below and you'll never be blindsided by a quote again.

What Is CBM?

CBM (cubic metre) is the volume of your shipment. For each carton:

CBM = Length (m) × Width (m) × Height (m)

A carton measuring 60 × 40 × 50 cm = 0.6 × 0.4 × 0.5 = 0.12 CBM. Multiply by the number of identical cartons to get total CBM. This is the headline number for sea freight (FCL/LCL), where space is the constraint.

What Is Volumetric (Chargeable) Weight?

Air and express carriers care about volume too, because a plane fills up by space long before it hits its weight limit. They convert your volume into a "volumetric weight" using a fixed divisor, then charge on the higher of volumetric vs actual weight.

Mode	Volumetric weight formula	Divisor
Air freight	(L × W × H in cm) ÷ 6000	6000
Express courier (DHL/UPS/FedEx)	(L × W × H in cm) ÷ 5000	5000
Sea LCL	Charged per CBM or per 1000 kg, whichever is greater	1 CBM ≈ 1000 kg

Note the express divisor (5000) is harsher than air (6000) — the same box has a higher chargeable weight by courier.

Worked Example: Light, Bulky Cargo

You're air-shipping 10 cartons of cushions. Each carton is 60 × 50 × 40 cm and weighs 8 kg.

• Actual weight: 10 × 8 kg = 80 kg
• Volume per carton: 60 × 50 × 40 = 120,000 cm³
• Volumetric weight per carton (air): 120,000 ÷ 6000 = 20 kg
• Total volumetric weight: 10 × 20 = 200 kg

The carrier charges on 200 kg, not 80 kg — because the cushions take up the space of 200 kg of cargo. This is why "it only weighs 80 kilos" doesn't match the quote.

Worked Example: Heavy, Dense Cargo

Now 10 cartons of machine parts, each 30 × 30 × 30 cm weighing 25 kg.

• Actual weight: 250 kg
• Volumetric weight: (27,000 ÷ 6000) × 10 = 45 kg

Here actual weight wins, so you're charged on 250 kg. Dense cargo is "weight-out"; light cargo is "volume-out".

How to Use This to Save Money

• Reduce dead air. Right-size cartons. Empty space in a box is space you pay for.
• Pick the right mode. Bulky-but-light cargo is punished hardest by express; air or sea may be far cheaper per real kilo.
• Consolidate smartly. Fewer, fuller cartons beat many half-empty ones.
• Give accurate dimensions. Carriers re-measure. Under-declaring dims leads to reweigh charges after the fact.

Quick Reference

If your cargo is…	You're billed on…	Watch out for…
Light & bulky (pillows, plastics)	Volumetric weight	Express divisor 5000 hurts
Heavy & dense (metal, liquids)	Actual weight	Pallet weight limits
Mixed	Per-carton higher of the two	Re-measure / reweigh fees

Bottom Line

Freight is priced on chargeable weight — the greater of actual and volumetric weight — and on CBM for ocean. Measure and weigh your cartons before you ask for a quote, and you'll understand the number instantly instead of being surprised by it. Send us your carton dimensions and weights and we'll calculate the chargeable weight and quote air, sea and express side by side. Start on our quote page.