CBM calculator

The calculator above converts dimensions into volume and into a chargeable figure. It does not produce a price. A price needs the lane, the commodity, the equipment and the state of the market on the day — what the calculator gives you is the number the rate is applied to, which is the part most shippers get wrong.

What CBM is, and the formula

A cubic metre (CBM) is the volume occupied by a piece of cargo. For a rectangular carton the formula is length x width x height, with all three sides in metres:

• CBM = L (m) x W (m) x H (m)
• Working in centimetres instead: CBM = (L x W x H in cm) / 1,000,000

Worked example (illustrative figures, not a quotation)

Take a carton measuring 60 cm x 40 cm x 30 cm. That is 72,000 cubic centimetres, or 0.072 CBM. Fifty identical cartons come to 3.6 CBM. If each carton has a gross weight of 18 kg, the consignment weighs 900 kg, or 0.9 metric tonnes.

Cartons to total CBM — measure the box, not the product

Carriers charge for the space a shipment occupies in the hold, not the space the goods would occupy if they were poured in loose. So the number that matters is the external dimension of the packed carton or the pallet, including the pallet itself, the shrink wrap and any overhang. Measure the longest point in each axis, round up, and add the cartons together. A product measuring 55 cm still travels as a 60 cm carton.

Sea LCL: CBM versus weight tonne, whichever is greater

Less-than-container-load ocean freight is conventionally charged on the revenue tonne — also written W/M, weight or measure. The convention takes the higher of the volume in CBM and the gross weight in metric tonnes, and bills that figure.

In the example above, 3.6 CBM against 0.9 tonnes gives 3.6 revenue tonnes. Dense cargo flips it: a consignment of 1.2 CBM weighing 2.5 tonnes is charged on 2.5. Treat W/M as an industry convention rather than a rule — some carriers and consolidators apply a different ratio or a minimum, so confirm the basis with the carrier before you budget. Our note on how ocean freight rates are built sets out the other components that sit alongside it.

Air freight: volumetric weight and chargeable weight

Air cargo is charged on chargeable weight, which is the greater of the actual gross weight and the volumetric (dimensional) weight. Volumetric weight is calculated by dividing the volume in cubic centimetres by a conventional divisor, commonly 6,000 for general air cargo — equivalent to treating one CBM as 167 kg. Courier and express traffic often uses a different divisor, so confirm which one applies to your booking.

• Volumetric weight (kg) = (L x W x H in cm) / 6,000
• Chargeable weight = the greater of actual gross weight and volumetric weight

The 3.6 CBM consignment above is 3,600,000 cubic centimetres, so its volumetric weight is 600 kg. Its actual weight is 900 kg, so it is charged on 900 kg. There is more detail in our guide to chargeable weight versus volumetric weight.

The same volume, two densities

Both consignments below are 50 cartons of 60 x 40 x 30 cm — 3.6 CBM. Only the weight differs. The figures are constructed to show the arithmetic, not to represent any real shipment.

Note what changes and what does not. On sea LCL both are billed identically, because volume governs in both cases. On air the dense consignment pays on its real weight while the light one pays for air it is not using. Density decides the mode as often as urgency does — compare ocean freight against air freight on the actual numbers.

How CBM maps to container fill

Nominal internal capacity is roughly 33 CBM for a 20ft general purpose, 67 CBM for a 40ft, and 76 CBM for a 40ft high cube. Treat these as conventions and confirm against the internal dimensions of the equipment actually released to you, which vary by build and by line.

Usable capacity is always less than nominal. Pallet footprints rarely tile a container without waste, fragile or top-heavy cargo limits the number of tiers, and the payload limit or a road weight restriction can fill the box by mass long before it fills by volume. Planning at 80 to 85 per cent of nominal is more realistic.

When LCL stops making sense

LCL carries its own handling and CFS costs per revenue tonne, and those do not fall as the consignment grows. Past roughly 13 to 15 CBM the all-in cost of an LCL booking often converges with a 20ft FCL, and the container brings fewer handling touches and less consolidation risk. Run both and compare — our piece on LCL versus FCL covers the trade-offs beyond price.

What a calculator cannot tell you

It cannot tell you what the shipment will cost. To quote, Scapex needs the destination port or airport, the commodity and HS code, gross weight, carton dimensions and count, the Incoterm, and the cargo ready date. Send those to our Ahmedabad office and we will come back with a basis you can check line by line.