CBM Calculator
Free CBM calculator: enter carton dimensions and count to get shipment volume in cubic metres, plus volumetric and chargeable weight. Carrier DIM divisors are presets to confirm against your carrier's current service guide.
CBM (cubic metres) is how freight measures size: multiply a carton's length, width, and height in metres, then multiply by the carton count. Forwarders quote sea and LCL rates per CBM, and parcel and air carriers convert the same volume into a volumetric weight to decide what you actually pay.
How it works
Enter the carton dimensions and count to get total volume in cubic metres. The tool then divides the volume by a carrier DIM divisor to estimate volumetric weight, and — when you enter an actual gross weight — shows the chargeable weight, which is simply the greater of the two. Advanced options switch carrier mode and divisor, check the load against common container sizes, and apply carrier-style rounding.
The formula
CBM = (L * W * H * Q) / 1,000,000 with dimensions in centimetres. Volumetric weight = (L * W * H * Q) / divisor, where the divisor is carrier-published in cm3/kg (or in3/lb for US parcel carriers). Chargeable weight = max(actual weight, volumetric weight).
Worked example
Ten cartons of 120 x 80 x 100 cm: (120 * 80 * 100 * 10) / 1,000,000 = 9.6 m3. At the air divisor of 6000, volumetric weight = 9,600,000 cm3 / 6000 = 1,600 kg. If the shipment actually weighs 900 kg on the scale, the chargeable weight is max(900, 1,600) = 1,600 kg — it is billed on volume, not on the scale weight.
Frequently asked questions
What divisor should I use?
It depends on carrier and service. Carrier-published figures, checked July 2026, are: 6000 cm3/kg for general air cargo (the IATA convention), 5000 cm3/kg for DHL Express and most express couriers, 139 in3/lb for FedEx and UPS Daily Rates in the US, 166 in3/lb for UPS Retail Rates, and 166 in3/lb for USPS (moving to 139 on 2026-07-12). Divisors change and can differ by rate card, country, and account agreement, so always confirm the value in your carrier's current service guide or contract before rating freight.
How is CBM used for sea and LCL freight?
LCL (less-than-container-load) rates are usually quoted per revenue tonne: the greater of the shipment's cubic metres and its weight in metric tonnes (1 CBM is treated as 1 tonne). A 9.6 m3 shipment weighing 900 kg is therefore billed as 9.6 revenue tonnes. Full containers are booked by container size instead — the tool's container-fit option shows how much of a 20ft, 40ft, 40ft HC, or 53ft unit your volume occupies.
What is chargeable weight and why is it higher than my scale weight?
Chargeable (billable) weight is the greater of actual weight and volumetric weight. Carriers charge for the space a shipment takes as well as its mass, so a light, bulky shipment is billed on its volume converted to weight through the DIM divisor. If your chargeable weight is above your scale weight, the shipment is volumetrically dense — better cartonisation or denser packing lowers the bill.
How many CBM fit in a shipping container?
Nominal capacities are roughly 33 m3 for a 20ft container, 67 m3 for a 40ft, 76 m3 for a 40ft high cube, and about 114 m3 for a 53ft US trailer. Real-world loadable volume is lower — typically 80-90% of nominal, depending on carton sizes and stacking — so treat the fill percentage as a planning estimate, not a load plan.
Related tools
This is a planning estimate. Results depend on your inputs and assumptions; confirm against your own data before ordering.
- Dimensions are entered in centimetres (1 m3 = 1,000,000 cm3).
- All cartons share the same outer dimensions.
- Volume is the simple sum of carton volumes; no packing or stacking loss is modelled.
- Dimensions are entered in centimetres and the divisor is in cm3 per kg, so the result is kilograms.
- No carrier rounding is applied inside the formula; carriers typically round dimensions and the final billable weight by their own rules.
- Actual and volumetric weight are expressed in the same unit before comparing.
- Volumetric weight is computed with the carrier's own current divisor.
- No final-weight rounding is applied inside the formula; carriers typically round the billable weight up (e.g. UPS to the next whole pound).