CBM calculator for cartons, sea freight and containers
This CBM calculator turns carton sizes into cubic metres (CBM), the unit freight forwarders use to price sea freight and to plan how much of a container your goods take. Enter the quantity and the length, width and height of up to four carton types, in centimetres, inches, millimetres, metres or feet, and you get the total CBM, the cubic feet, the volumetric weight for air freight and the sea freight tonne.
It also shows how much of a 20 ft, 40 ft and 40 ft high-cube container the load fills by volume, so you can see at a glance whether a shipment is a part load (LCL) or closer to a full container (FCL). Everything is calculated in your browser.
How to use the CBM Calculator
- Pick the unit your carton sizes use. Inches work as well as centimetres.
- For each carton type enter the number of cartons, the length, width and height, and optionally the weight of one carton in kg.
- Choose the air volumetric divisor your carrier uses: 6000 for the IATA standard, 5000 for many couriers or your own figure.
- Set the usable share of a container (85 % is a cautious start).
- Read the total CBM, the chargeable air weight, the sea freight tonne and the container bars.
CBM Calculator features
Several carton types
Up to four lines are added together, each with its own quantity and optional weight.
Any unit
cm, inches, mm, metres or feet; results in CBM, cubic feet and litres.
Air and sea charging
Volumetric kg for air, the greater of volume and weight for air, and the W/M freight tonne for sea.
Container fill
How much of a 20 ft, 40 ft and 40 ft high cube the volume takes, and how many you would need.
Editable assumptions
Divisor and usable share are yours to change, since carriers and loading methods differ.
How to calculate CBM
CBM is length × width × height of a carton in metres, multiplied by the number of cartons. If your sizes are in centimetres, divide the product by 1,000,000. Example: a carton of 50 × 40 × 30 cm is 60,000 cm³, or 0.06 CBM; 100 such cartons are 6 CBM. In inches, multiply the cubic inches by 0.0000163871. One CBM is 35.31 cubic feet.
Use the outer size of the packed carton, including any bulge. Rounding each side up before multiplying is what many forwarders do, so allow a little extra for a safe estimate.
From CBM to kilograms: air and sea
There is no single conversion from CBM to kg: it depends on the mode and carrier. Air freight charges the larger of actual and volumetric weight; the divisor is set by the airline or courier. Sea LCL freight is usually charged per freight tonne, the greater of 1 m³ or 1,000 kg. The calculator shows which one wins. For courier dimensional-weight rules per parcel, see the volumetric weight calculator.
| Mode | Rule | Per 1 CBM |
|---|---|---|
| Air (IATA standard) | volume in cm³ ÷ 6000 | 167 kg |
| Air (many couriers) | volume in cm³ ÷ 5000 | 200 kg |
| Sea LCL | greater of CBM or tonnes (W/M) | 1,000 kg |
How much fits in a container?
Sizes follow the Maersk container equipment guide for ISO 668 steel dry containers; other makers differ by a few millimetres. In practice cartons never fill every cubic metre, so the calculator applies your usable share. For the exact count of cartons or pallets, with orientation and payload, use the container loading calculator; for pallets, the pallet calculator.
| Container | Internal size (m) | Volume |
|---|---|---|
| 20 ft | 5.896 × 2.350 × 2.393 | 33.2 m³ |
| 40 ft | 12.032 × 2.350 × 2.393 | 67.7 m³ |
| 40 ft high cube | 12.032 × 2.350 × 2.697 | 76.3 m³ |
CBM Calculator FAQ
How do I calculate CBM?
Multiply length × width × height in metres, then by the number of cartons. For centimetres, multiply the three sizes and divide by 1,000,000. A 60 × 40 × 40 cm carton is 0.096 CBM.
How do I calculate CBM in inches?
Multiply length × width × height in inches to get cubic inches, then multiply by 0.0000163871. A 20 × 20 × 20 in carton is 8,000 in³, which is 0.131 CBM.
How many kg is 1 CBM?
It depends. For sea freight, 1 CBM is charged as 1,000 kg if the cargo weighs less than that (W/M rule). For air, 1 CBM is 167 kg at the IATA 6000 divisor or 200 kg at 5000.
How many CBM are in a 20ft and a 40ft container?
About 33 CBM in a 20 ft, 67 CBM in a 40 ft and 76 CBM in a 40 ft high cube internally. Practical loads are lower because of carton shapes and gaps.
What is chargeable weight?
The greater of the actual weight and the volumetric weight. The carrier bills that figure for air freight; its divisor appears on the quote.
Is the container result exact?
No. It compares volumes only. Carton orientation, pallets, door size and the payload limit change the real count, which the container loading calculator works out.