CBM Calculator (Cubic Meters for Shipping)
Calculate CBM from carton size and quantity in cm, mm, m, inches or feet, with cubic feet, W/M revenue tons and air volumetric weight.
CBM (cubic metres) is the unit freight forwarders use to price sea freight, especially LCL (less than container load) shipments. This calculator turns your carton size and count into total CBM and cubic feet, shows revenue tons under a common W/M model, and gives the volumetric weights used for air and courier pricing.
How to use this tool
- Choose the unit your carton dimensions are measured in.
- Enter the length, width and height of one carton.
- Enter the number of identical cartons.
- Enter the gross weight of one carton and choose kg or lb.
Formula
CBM = length (m) × width (m) × height (m) × number of cartons
Convert to metres first (cm ÷ 100, inches × 0.0254). 1 m³ = 35.315 ft³. The selected sea freight W/M model uses the greater of CBM and metric tonnes. Air volumetric weight is cm³ ÷ 6,000, which is 166.67 kg per CBM; express couriers often use ÷ 5,000, or 200 kg per CBM.
Example
100 cartons of 50 × 40 × 30 cm: 0.5 × 0.4 × 0.3 = 0.06 m³ per carton, so the shipment is 6 CBM, or 211.89 ft³. At 8 kg per carton it weighs 800 kg (0.8 tonnes), so the W/M model charges on 6 revenue tons because volume is the larger figure. By air the same cartons would be billed on 1,000 kg of volumetric weight, more than their actual weight.
Frequently asked questions
How do I calculate CBM from inches?
Multiply length × width × height in inches to get cubic inches, then multiply by 0.000016387064 to get cubic metres. Choose inches above and the calculator does the conversion.
How many CBM fit in a 20 ft or 40 ft container?
The internal volume is about 33.2 m³ for a 20 ft, 67.7 m³ for a 40 ft and 76.4 m³ for a 40 ft high cube. Gaps between cartons mean you will load less than that; the container load calculator checks the real fit for your carton size.
What does W/M mean in sea freight?
Weight or measurement. This model uses one revenue ton per CBM or per 1,000 kg, whichever is larger. The applicable tariff may add minimum quantities, dimension rounding, shipment fees and other charges; confirm these with your forwarder.
Should I measure the carton or the pallet?
Measure what the carrier handles. If the cartons travel on pallets, measure the whole loaded pallet, including the base and any overhang, because that is the space it takes.
Sources
Last updated: 2026-10-30