How to Calculate CBM for Shipping: Formula & Examples

CBM is the unit that sea freight from China is measured and priced in, so knowing how to calculate CBM tells you what you will pay for LCL, whether a full container makes sense, and how air freight will bill a light, bulky shipment. This guide gives the CBM formula in centimetres and inches, worked examples for one carton and a whole shipment, the chargeable weight rules for sea, air and express, and how many cartons fit in a container.

Key points
• CBM means cubic metre. One CBM is a space 1 m long, 1 m wide and 1 m high.
• CBM of a carton = length × width × height in cm ÷ 1,000,000. Multiply by the number of cartons for the shipment.
• Sea LCL is charged on CBM or weight, whichever is greater, with 1 CBM counted as 1,000 kg.
• Air freight bills volume weight at L × W × H (cm) ÷ 6,000 per carton; express uses ÷ 5,000.
• A 20ft container takes about 25–28 CBM of cartons, a 40ft about 55–58 CBM and a 40ft high cube about 65–68 CBM.

What Is CBM in Shipping?

CBM stands for cubic metre (m³). Forwarders and shipping lines use it to measure how much space your goods take. In sea freight it decides the price of a shared container (LCL), and it tells you how much of a 20ft or 40ft container your goods will fill. Your supplier’s packing list usually shows the carton size and the total CBM, but it is worth checking the figure yourself, because a wrong CBM means a wrong quote.

The CBM Formula

How to Calculate CBM: Worked Examples

One carton

A carton measures 55 × 45 × 35 cm. 55 × 45 × 35 = 86,625 cm³. Divided by 1,000,000, that is 0.087 CBM.

A whole shipment

Multiply the CBM of one carton by the number of cartons, then add up each carton size on the packing list.

Work out the total from the exact figure for each carton size before rounding (55 × 45 × 35 cm is 0.086625 CBM, so 60 cartons are 5.20 CBM). Rounding each carton first adds up to a noticeable error on large shipments.

Carton sizes in inches

A carton of 24 × 18 × 18 inches is 7,776 cubic inches. Divided by 61,024, that is 0.127 CBM. If you work in cubic feet, divide by 35.315 instead.

Pallets

For palletised cargo, measure the whole pallet, including the wooden base and any overhang. A pallet of 120 × 100 cm loaded to 150 cm high is 1.2 × 1.0 × 1.5 = 1.8 CBM, even if the cartons on it add up to less. Pallets protect the cargo but add volume, so ask whether your cargo really needs them for LCL.

CBM for Irregular Items

Not everything ships in a neat carton. For irregular cargo, measure the smallest box the item would fit into:

• Machines and crates: measure the outside of the crate or the longest, widest and highest points of the machine, including any handles or parts that stick out.
• Cylinders, drums and rolls: use diameter × diameter × height. A drum 60 cm across and 90 cm high takes 0.6 × 0.6 × 0.9 = 0.32 CBM of space.
• Bundles of pipes or profiles: length × width × height of the whole bundle.

Carriers charge for the space an item blocks, not its exact shape.

CBM to Cubic Feet

Common CBM Mistakes

• Using product size instead of carton size. Freight is charged on the outside of the packed carton.
• Mixing centimetres and inches on the same packing list.
• Forgetting pallets and the height of the wooden base.
• Rounding each carton before multiplying by the number of cartons.
• Using a supplier estimate made before final packing.

Common Carton Sizes: CBM at a Glance

Cartons never fill every gap, so the number that really fits is a little lower than the volume suggests. For any other size, our freight calculator works out the CBM, the chargeable weight and the container fill for a full packing list.

CBM and Chargeable Weight: Sea, Air and Express

Freight is charged on space or weight, whichever is greater. Each mode converts volume to weight in its own way:

Example. 30 cartons of 55 × 45 × 35 cm weighing 9 kg each: 2.6 CBM and 270 kg in total.

• Sea LCL: 2.6 CBM is more than 0.27 tonnes, so you pay for 2.6 CBM.
• Air freight: volume weight per carton is 86,625 ÷ 6,000 = 14.4 kg, more than the 9 kg actual weight, so you pay for about 433 kg, not 270 kg.
• Express: 86,625 ÷ 5,000 = 17.3 kg per carton, so about 520 kg is billed.

Light, bulky goods are expensive to fly because they are billed on size. For formulas, worked examples and a calculator, see our guide to chargeable weight. Heavy goods, such as metal parts or tiles, are often billed on weight even by sea. Our guide to air freight vs sea freight compares the two in more detail.

How Many CBM Fit in a Container?

Heavy cargo often reaches the weight limit before the container is full. Below about 13 CBM, LCL is usually cheaper than a 20ft container. Between about 13 and 28 CBM, compare both prices: the turning point depends on the route, and a full container is always faster. See LCL vs FCL for how to choose, and our guide to the cost to ship a container from China.

How to Reduce CBM and Lower Your Freight Cost

• Ask for smaller cartons. Less empty space and less filler means fewer CBM for the same goods.
• Use stackable or flat-packed products where you can, such as nested items or knock-down furniture.
• Skip pallets for LCL unless the cargo or the destination warehouse needs them.
• Check the packing list. Suppliers sometimes round carton sizes up or list the wrong size. Ask for photos of a measured carton.
• Combine suppliers so the total reaches a full container sooner. See our China consolidation services and the cheapest way to ship from China.

How JIEYI Uses Your CBM

We are a freight forwarder in Dongguan shipping from South China by sea, air and express. Send us your packing list with carton sizes, weights and quantities, and we check the CBM, tell you whether LCL or a full container is better, and quote door to door.

Send us your packing list for a quote.

How to Calculate CBM: FAQ

What is the formula for CBM?

Length × width × height in centimetres, divided by 1,000,000. For example, 50 × 40 × 40 cm = 80,000 cm³ = 0.08 CBM.

How do I calculate CBM in inches?

Multiply length × width × height in inches and divide by 61,024. A carton of 24 × 18 × 18 inches is 0.127 CBM.

How many kg is 1 CBM?

CBM is a volume, not a weight. For pricing, sea LCL counts 1 CBM as 1,000 kg, air freight as about 167 kg, and express as 200 kg.

How many CBM is a 20ft container?

A 20ft container has about 33 CBM inside, but a realistic load of cartons is about 25–28 CBM. A 40ft takes about 55–58 CBM and a 40ft high cube about 65–68 CBM.

How much does it cost to ship 1 CBM from China?

By sea LCL in November 2026, the main freight is about $120–150 per CBM to the US West Coast and about $60–90 per CBM to the UK, plus origin and destination charges. See LCL shipping from China.

How do I calculate CBM for a cylinder?

Use diameter × diameter × height in metres, because the cylinder blocks a square space. A drum 0.6 m across and 0.9 m high is about 0.32 CBM.

Is the CBM on my supplier’s packing list correct?

Usually, but not always. Check it with the carton sizes and the number of cartons. The final CBM for LCL is measured at the warehouse, so a packing list that is too low will lead to a higher invoice.

Once you know your CBM, check which container fits it in our guide to shipping container dimensions.

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Checked on November 4, 2026. Volume conversions are the standard ones used by most carriers; some airlines and couriers use different divisors, so confirm with your forwarder. Send us your packing list and we will check the CBM in your quote.