CBM Calculator

How the CBM calculator works

CBM (cubic metres, m³) is the unit ocean freight runs on. LCL consolidators charge per CBM, container capacity is quoted in CBM, and suppliers in China, India and Southeast Asia put it on every packing list. This calculator adds up any number of carton sizes and tells you where the total lands.

• Pick your units for dimensions (cm, mm, inches or metres) and weight (kg or lb). Every line uses the same units.
• Enter one line per carton size with its outside dimensions and the number of cartons. Carton weight is optional but needed for the W/M figure and the payload check.
• Read the label: total m³, the same volume in ft³, total weight, and W/M (the greater of cubic metres and metric tonnes, which is what LCL is billed on).
• Read the container table. It compares your total with the space you can realistically load in each container, not the brochure figure, and says how many boxes you would need by volume or by weight, whichever runs out first.

The table works by volume only. To find how many cartons of one size physically fit, with orientation and stacking, use the container loading calculator.

CBM formulas

Worked example: a mixed consolidation from Ningbo

An online seller is bringing in three products in one shipment:

That is 710 ft³ and a W/M of 20.11, because 20.11 m³ is more than 3.21 tonnes. As LCL it would be billed on 20.11 revenue tonnes. In a 20-foot container it uses about 72 % of the roughly 28 m³ you can realistically load, so a 20′ FCL is the obvious comparison, and there is room to add stock to the order.

How much fits in each container

The nominal capacity of a 20′ box is about 33 m³ and a 40′ high cube about 76 m³, but cartons never fill every corner, the door end needs clearance, and loads are braced. The table uses the practical figures freight forwarders plan with: about 28 m³ for a 20′, 58 m³ for a 40′, 68 m³ for a 40′ HC and 76 m³ for a 45′ HC. Well-matched, uniform cartons can beat those numbers; mixed loads and fragile goods often fall short.

Dense cargo such as tiles, stone, metal parts or bagged chemicals reaches the payload limit long before the box is full. When the table marks a container as weight-bound, the cube figure stops mattering. In many countries road weight limits for the truck carrying the container are lower still, so ask your haulier before loading a 20′ to its rated payload.

Mistakes that inflate the freight bill

• Rounding each carton before multiplying. 0.077 m³ rounded to 0.08 and multiplied by 120 cartons gives 9.6 m³ instead of 9.24, almost 4 % extra on an LCL invoice. Round the total, not the parts.
• Mixing millimetres and centimetres. A packing list in mm entered as cm is a thousand times too big. If a carton comes out at 120 m³, check the units.
• Measuring loose cartons when the cargo ships palletised. The consolidator bills the pallet: its footprint, its deck height and any overhang. Measure the built pallet.
• Forgetting the LCL minimum. Most consolidators charge at least 1 CBM (or 1 W/M) per shipment, so a 0.3 m³ parcel of samples is often cheaper by express.
• Planning a container on the nominal cube. Booking a 20′ for 32 m³ of cartons usually means cargo left on the dock.