CBM Calculator for Cartons and Shipments

CBM means cubic meter (m³), the unit of volume used to price sea freight and to plan container loads. To calculate the CBM of a carton, multiply its length, width and height in meters. Multiply that by the number of cartons for the shipment total.

CBM formula: CBM = length (m) × width (m) × height (m) × number of cartons

If you measure in centimeters, divide the result of length × width × height by 1,000,000. In inches, divide by 61,023.74.

Worked example

You ship 20 cartons of 60 × 40 × 50 cm, each weighing 18 kg.

1. One carton: 0.60 × 0.40 × 0.50 = 0.12 CBM.
2. Shipment: 0.12 × 20 = 2.4 CBM, which is 84.76 cubic feet.
3. Gross weight: 18 × 20 = 360 kg.
4. Sea freight (LCL) charges the greater of 2.4 CBM and 0.36 tonnes, so you pay for 2.4 W/M.
5. By air, the volumetric weight is 2,400,000 cm³ ÷ 6000 = 400 kg, more than the 360 kg actual weight, so you pay for 400 kg.

How is CBM used to charge sea freight?

For a shared container (LCL), forwarders charge per "weight or measure" (W/M): one CBM is treated as one tonne, and you pay for whichever is greater. Light, bulky goods pay by volume; dense goods such as tiles or metal parts pay by weight. Most LCL rates also have a minimum charge, often 1 CBM. For a full container (FCL) you pay per box, so CBM tells you how many containers you need; see shipping container dimensions for the usable space.

How many CBM fit in a container?

A 20 ft container has about 33 CBM of inside space, a 40 ft about 67 CBM, and a 40 ft high cube about 76 CBM. You will rarely fill all of it: carton sizes leave gaps, pallets take room, and cartons must be stacked safely. As a rough planning guide, many shippers expect 25 to 28 CBM in a 20 ft and 55 to 58 CBM in a 40 ft. The calculator shows your volume as a share of each container so you can see when a shipment moves from LCL to a full container.

Container	Inside volume	Typical loaded volume
20 ft standard	33.2 CBM	25 to 28 CBM
40 ft standard	67.7 CBM	55 to 58 CBM
40 ft high cube	76.3 CBM	65 to 68 CBM

Tips for measuring cartons

• Measure the packed carton, at its widest points, including any bulge. Forwarders measure what arrives at the warehouse.
• Measure pallets as a whole when goods ship palletised: length and width of the pallet base and the height from the floor to the top of the cargo.
• Round up, not down. A carton measured at 59.6 cm should be entered as 60 cm.
• Put the volume on your documents. The CBM and gross weight per line belong on the commercial invoice and packing list, and the totals on the bill of lading.

Converting CBM to other units

1 CBM = 35.3147 cubic feet = 1,000 liters = 1,000,000 cubic centimeters. Use the CBM to CFT converter when a US supplier or forwarder works in cubic feet.