About this calculator
Add the carton weight to see what you will be charged on: air freight and couriers use the greater of actual and volumetric weight, and sea freight uses the greater of volume in CBM and weight in tonnes.
How to use it
- Enter length, width and height of one carton and the unit.
- Enter the number of cartons and, if known, the weight of one.
- Read the CBM, chargeable weight and container fit.
The formula
CBM = length × width × height (in metres) × number of cartons; volumetric weight (air) = L × W × H in cm ÷ 6,000
- ÷ 6,000
- air freight divisor; couriers often use 5,000
- W/M
- sea freight: 1 CBM or 1,000 kg, whichever is greater
Worked example
100 cartons of 60 × 40 × 50 cm at 18 kg each
- One carton = 0.12 CBM; total = 12 CBM.
- Volumetric weight by air = 2,000 kg against 1,800 kg actual, so you pay for 2,000 kg.
What the result means
Light, bulky cargo is charged by volume; dense cargo by weight. Smaller cartons or tighter packing reduce the chargeable weight.
Assumptions
- Rectangular cartons.
Limitations
- Container fit is by volume only; real loading depends on carton shape, stacking and the weight limit.
Frequently asked questions
How do I calculate CBM?
Multiply length × width × height in metres. In centimetres, divide the product by 10,00,000.
How many CBM fit in a 20 ft container?
About 33 CBM inside, of which roughly 28 is usable. A 40 ft holds about 58 usable, and a 40 ft high cube about 68.
What is chargeable weight?
The greater of the actual weight and the volumetric weight.
Last reviewed on 7 October 2026. Found a mistake? Tell us.