Cubic Meter (CBM)

What it means

A cubic meter is the SI unit of volume. In shipping it is written CBM, m3 or m³. NIST lists 1 cubic meter as 35.314 67 cubic feet, and 1 cubic foot as exactly 0.028 316 846 592 cubic meter.^[1] Most people round to 35.3147 or 35.31.

Ocean freight is sold by space as well as weight. Carriers state container capacity in CBM, and LCL (less than container load) rates are usually quoted per CBM or per revenue ton. If you can measure your cartons, you can work out your CBM, compare it with what a container holds and check a quote.

How to calculate CBM from centimeters

Most carton labels list size in centimeters. You have two easy ways to get CBM.

1. Convert each side to meters by dividing by 100, then multiply. A 60 x 40 x 40 cm carton is 0.6 x 0.4 x 0.4 = 0.096 m3.
2. Or multiply the three sides in centimeters, then divide by 1,000,000. 60 x 40 x 40 = 96,000 cm3, and 96,000 / 1,000,000 = 0.096 m3.
3. Multiply by the carton count. 200 cartons x 0.096 = 19.2 CBM.

Round each side up to the nearest whole centimeter. Bulges, handles and pallet overhang all take space, and the receiving warehouse will measure what it sees.

How to calculate CBM from inches

NIST lists 1 cubic meter as 61 023.74 cubic inches, and 1 cubic foot as 1,728 cubic inches.^[1] So:

• CBM = L x W x H in inches / 61,024. A 24 x 16 x 16 in carton is 6,144 in3, or about 0.1007 m3.
• Cubic feet = L x W x H in inches / 1,728. The same carton is about 3.56 ft3.
• If you have dimensions in feet, multiply them to get cubic feet, then divide by 35.3147 to get CBM.

The CBM calculator does this math for mixed cartons and units. Use it when you have more than one carton size.

CBM to cubic feet (CBF) conversion

To go from CBM to cubic feet, multiply by 35.3147. To go from cubic feet to CBM, multiply by 0.0283168 or divide by 35.3147.^[1]

For other unit swaps, such as kilograms to pounds, use the unit converter.

CBM and the LCL weight or measure (W/M) rule

In LCL, your cargo shares a container with other shippers, so you pay for your share. Most LCL tariffs use the weight or measure rule, written W/M. The forwarder compares your volume in CBM with your weight in metric tons (1,000 kg) and charges on whichever is greater.^[3]

The billed unit is often called a revenue ton (RT). One forwarder states it as "1 RT = 1 CBM or 1,000 kg (1 MT), whichever is higher."^[3] So 1 CBM and 1,000 kg are treated as equal for rating only. This is a pricing rule, not a physical conversion.

• Light cargo (under 1,000 kg per CBM) is billed on volume.
• Heavy cargo (over 1,000 kg per CBM) is billed on weight.
• Many tariffs also set a minimum, such as 1 RT, so a very small shipment is billed as if it were 1 CBM.^[3]

Some tariffs use other thresholds, so read the W/M line on your own quote. For when a full container beats LCL, see FCL vs LCL.

How many CBM fit in a 20 ft and 40 ft container

Carriers publish container volume in CBM. One Maersk equipment sheet lists these steel dry containers:^[2]

These are the full inside volumes. You will not fill every cubic meter. Carton sizes rarely divide evenly into the box, pallets leave gaps, and the door opening is smaller than the inside. Specs also vary by carrier and box, so check your carrier's sheet. To test a real load plan, use the container loading calculator. See also the 20 ft container and 40 ft container entries.

How many pallets are in 10 CBM?

It depends on pallet size and height, so work it out from the pallet's own CBM. Illustrative math only:

• A 120 x 100 cm pallet loaded to 150 cm high is 1.2 x 1.0 x 1.5 = 1.8 CBM. Ten CBM holds 5 of these (10 / 1.8 = 5.6).
• A 48 x 40 in pallet loaded to 60 in high is about 1.89 CBM. Ten CBM again holds 5 full pallets.

Measure the pallet with the freight on it, at its tallest point. The pallet calculator helps plan cartons per pallet.

Why it matters

CBM drives LCL cost, container choice and warehouse space. A wrong measurement can mean a re-rated invoice or cargo that does not fit the booked box. RapidShips runs a warehouse dock in East Brunswick, NJ, where we unload, count and stage container freight. We are not a carrier or forwarder, so your carrier or forwarder's tariff sets the actual rate.

Example

Illustrative only, not a real job or quote. A shipper has 200 cartons, each 60 x 40 x 40 cm and 15 kg. Volume: 0.096 x 200 = 19.2 CBM, or about 678 cubic feet. Weight: 200 x 15 = 3,000 kg, or 3.0 metric tons.

Under W/M, 19.2 is greater than 3.0, so an LCL quote would bill 19.2 revenue tons. At 19.2 CBM the load is well over half of a 33 m3 20 ft box, so it is worth pricing a full container too.

Illustrative heavy case. Two CBM of floor tile weighing 2,600 kg is 2.6 metric tons. Weight is greater, so it bills as 2.6 RT.

Common mistakes

• Mixing units. Multiplying centimeters and calling the result CBM gives a number 1,000,000 times too big.
• Measuring the product, not the package. CBM is based on outside carton or pallet size.
• Treating 1 CBM = 1,000 kg as real density. It is only the W/M comparison point.^[3]
• Planning to the nominal container volume. A 33 m3 box will not take 33 m3 of cartons.

Frequently asked questions