CBM full form: what it means and how to calculate it

CBM stands for cubic metre, written cubic meter in American English, the unit shipping uses for cargo volume, so when a mover tells you your household goods come to a number of CBM, it means the space they will take up in a container, worked out from their length, width and height in metres.

So the CBM full form is simply cubic metre. One CBM is the space inside a cube that measures a metre along every edge.

This guide gives the formula, a worked example, and the conversions from cm and inches. It then shows what CBM decides in a move abroad, from the container to the air shipment.

For how a whole move from India runs, see international movers from India.

In shipping, CBM is the volume your goods fill, the measure carriers, forwarders and movers use to say how big a shipment is, and for a household move the space is usually what has to be planned, because a home is mostly bulky, light things such as sofas, mattresses and cartons of clothes.

CBM is the shipping code for the cubic metre (m³). The cubic metre is also the SI unit of volume, according to the US National Institute of Standards and Technology.

So CBM and m³ are the same unit. Only the way it is written differs. A packing list may show either.

You will meet the term on a survey report, a packing list and a bill of lading. The glossary entry for CBM sits beside the other shipping terms a move uses.

To calculate CBM, measure an item's length, width and height in metres and multiply the three together, so a carton 0.6 m long, 0.5 m wide and 0.5 m high comes to 0.15 CBM, and you then add up every carton and piece of furniture to get the total CBM of the shipment.

The formula is length × width × height, with all three dimensions in metres. Use the outside measurements of the box, not the space inside it.

Work through a shipment in this order:

1. Measure the length, width and height of each item
2. Write each one in metres
3. Multiply the three to get its CBM
4. Multiply by the number of identical items
5. Add the results to get the total

A worked example

Say you are sending thirty cartons of the same size, each 0.6 m × 0.5 m × 0.5 m. Each carton is 0.15 CBM, so thirty of them come to 4.5 CBM.

Add a sofa that measures 2.0 m × 0.9 m × 0.8 m. It comes to 1.44 CBM on its own.

The two together are 5.94 CBM. That is the cargo volume of this small shipment. A real home has many more items.

To convert measurements in cm, divide each dimension by 100 before you multiply, or multiply the three cm figures and divide the answer by 1,000,000, and for inches, multiply each dimension by 0.0254 to get metres, because one inch is 2.54 cm and the formula only gives CBM when every measurement is in metres.

From cm

A carton of 60 cm × 50 cm × 50 cm becomes 0.6 m × 0.5 m × 0.5 m. That is 0.15 CBM, as above.

Multiplying the cm figures first gives 150,000 cubic centimetres. Divide by 1,000,000 and you reach the same 0.15 CBM.

From inches

One inch is 2.54 cm, or 0.0254 m, the conversion factors the NIST guide to SI units lists. A carton of 24 × 18 × 18 inches is 0.6096 m × 0.4572 m × 0.4572 m.

Multiply those and the carton is about 0.13 CBM. Round only at the end, so small errors do not add up across many cartons.

Keep to one unit for the whole list. A mix of cm and inches is an easy slip to make.

CBM matters when you move abroad because the total volume of your goods decides how much of a container they need, and so whether the sea part of the move shares a container with other shippers' cargo or has one of its own, which shapes the time, the handling and what the move costs.

A smaller load usually shares a container, known as LCL, less than container load. A load that fills most of a box usually suits a full container load, or FCL. The LCL vs FCL guide compares the two.

The volume is only one of the things a quote rests on. These also shape it:

• Whether your goods share a container or have their own
• Which container size a full load needs
• Packing and crating, which add to the volume
• Any part of the move that goes by air, where bulky, light pieces count by their size

A pre-move survey turns your home into a CBM figure, room by room. Show everything that is going, and say what stays.

When you are ready, you can ask for a moving quote based on a survey of your goods.

An empty standard 20-foot dry container holds about 33 cubic metres inside, a 40-foot about 68 cubic metres and a 40-foot high cube about 76 cubic metres, according to the reference figures that the carriers Ocean Network Express and Hapag-Lloyd publish, though household goods never fill a box completely.

The table sets the three common dry containers side by side.

The figures come from Ocean Network Express container specifications and Hapag-Lloyd's container specification. Both carriers give them for reference, and individual containers differ a little.

This is the container capacity of an empty box. Cartons, sofas and tables leave gaps between them, so your goods fit in less than this.

The door is also smaller than the inside. Check very large pieces before they are packed.

Volumetric weight (also called volume weight) is the weight an airline gives a shipment for the space it fills, worked out from its dimensions, and air freight is charged on the greater of that and the actual weight on the scale, so bulky, light household goods are charged for their size rather than what they weigh.

The airline sets how dimensions turn into a volume weight. Ask your mover which method applies, and measure carefully.

Sea freight works differently. There, the question is how much of a container your goods fill.

This is why a few dense cartons suit air and furniture suits sea. Books are dense, and pillows are not.

The sea freight vs air freight guide explains how to split shipments between the two.