CBM Calculator
Cubic metres (CBM) and weight of a shipment of cartons, and how many cartons a 20 ft, 40 ft or 40 ft high-cube container takes by volume and by payload.
Result…
How it's calculated
Carton CBM = length × width × height (cm) ÷ 1 000 000 (inches: L × W × H × 0.0254³ m³, or ÷ 1728 for ft³) Total CBM = carton CBM × number of cartons Cartons by volume = capacity × usable share ÷ carton CBM, rounded down Cartons by payload = max payload ÷ carton weight, rounded down Cartons that fit = the smaller of the two
Works out the volume of a shipment in cubic metres (CBM), the unit freight forwarders quote for sea freight, and its weight, and then how many of your cartons a 20 ft, 40 ft or 40 ft high-cube container takes, limited by volume and by payload. The example capacities and payloads are Hapag-Lloyd's published figures (20 ft standard 33.2 m³ and 28 130 kg; 40 ft 67.7 m³ and 28 750 kg; 40 ft high cube 76.3 m³ and 28 600 kg); other carriers' containers differ, so you can type your own. Dividing the volume gives a theoretical count: the real loadable volume is lower, so set a usable share if your forwarder plans with one.
Your numbers, step by step
About the CBM calculator
This CBM calculator works out the cubic metres of a shipment of cartons, the unit forwarders use to quote sea freight and groupage, and its total weight. Enter the carton length, width and height in centimetres or inches, the number of cartons and the packed weight of each. It then shows how many cartons a 20 ft, 40 ft and 40 ft high-cube container takes, both by volume and by payload, and uses the smaller. The example capacities and payloads are Hapag-Lloyd's published figures for its standard containers; other carriers' boxes differ, so you can type your own. Dividing volumes gives a theoretical count, and the real loadable volume is lower because cartons never fill a container exactly, so you can set a usable share. Every step shows your own numbers, in m³ and ft³.
How to use it
- Choose metric (cm and kg) or imperial (in and lb) units.
- Enter the “Carton length”, “Carton width” and “Carton height”, measured outside the packed carton.
- Enter the “Number of cartons” and the “Weight per carton”, or 0 to leave weight out.
- Set the “Usable share of the container” if your forwarder plans with less than the full volume.
- Check the capacity and max payload for each container against your carrier's figures, then read the total CBM and the cartons each container holds.
Worked example
400 cartons of 50 × 40 × 30 cm, 15 kg each. One carton is 50 × 40 × 30 ÷ 1 000 000 = 0.06 m³, so the shipment is 0.06 × 400 = 24 m³ (about 847.6 ft³) and weighs 6000 kg. A 20 ft container of 33.2 m³ holds 33.2 ÷ 0.06 = 553 cartons by volume, and its 28 130 kg payload would allow 1875, so volume is the limit and the whole shipment fits in one 20 ft container. A 40 ft holds up to 1128 and a 40 ft high cube up to 1271.
Updated
Questions people ask
How do I calculate CBM for cartons?
Multiply the carton's length, width and height in centimetres and divide by 1 000 000 to get cubic metres, then multiply by the number of cartons. In inches, divide L × W × H by 61 023.7 (or by 1728 for cubic feet).
How many CBM fit in a 20 ft container?
Hapag-Lloyd lists its 20 ft standard at 33.2 m³ internal capacity, its 40 ft at 67.7 m³ and its 40 ft high cube at 76.3 m³, with payloads of 28 130, 28 750 and 28 600 kg. Other carriers' figures differ slightly, so check your carrier's specification (Hapag-Lloyd 20 ft standard).
Why can't I load the full container volume?
Cartons rarely divide the internal length, width and height exactly, and pallets, dunnage, bracing and the door opening take space. The real loadable volume is lower than the theoretical one, so treat the volume count as an upper limit and ask your forwarder for a load plan.
Which limit applies first, volume or weight?
Light, bulky goods fill the volume first; dense goods such as tiles or metal reach the payload first. The calculator works out both for each container and uses the smaller count.
What doesn't this CBM estimate cover?
It doesn't check that cartons fit through the door or stack safely, and road weight limits on the route may allow less than the container's payload. Freight is often charged on volume or weight, whichever is greater, so ask your forwarder for the rule they use. To convert units, see the volume converter.