What is the CBM Calculator?
CBM (cubic metre) is the language of freight. Forwarders quote LCL sea freight per CBM and use it to decide container sizes. The CBM calculator adds up to three carton sizes with their quantities and shows total CBM, cubic feet, gross weight and container fill.
For air freight, convert CBM to chargeable weight with the CBM to KG Calculator; for one carton size only use the Carton Volume Calculator. All calculators accept centimetres, inches or millimetres and kilograms or pounds, so you can use the units on your supplier's spec sheet.
How to use the CBM Calculator
- Enter each carton size and quantity (up to three).
- Enter the weight per carton (optional).
- Choose cm or inches.
- Read total CBM, cubic feet and container fill.
Formula
CBM = length (m) × width (m) × height (m) × quantity · cm: L × W × H ÷ 1,000,000
Example
100 cartons of 50 × 40 × 30 cm (0.06 m³) plus 50 cartons of 60 × 40 × 40 cm (0.096 m³) = 6 + 4.8 = 10.8 CBM, about 33% of a 20ft container.
CBM quick facts
- 1 CBM = 35.315 cubic feet.
- A 20ft container fits about 25–28 CBM in practice.
- A 40ft fits about 55–58 CBM; a 40ft HC about 65–68 CBM.
- Sea freight treats 1 CBM as 1,000 kg (W/M).
Related packaging and shipping tools
Packaging decisions are connected: the box size sets the volumetric weight, which sets the courier bill, and the carton size decides how many fit on a pallet or in a container. These related calculators help with the next step:
- Volumetric weight calculator: courier, air, sea and road.
- Dimensional weight calculator: DIM weight and chargeable weight.
- Shipping cost calculator: courier cost from your rate card.
- Freight cost calculator: air, LCL, FCL and road.
- Package weight calculator: gross weight of a packed box.
Frequently asked questions
How do I calculate CBM?
Multiply length, width and height in metres, then by the number of cartons.
How do I calculate CBM from centimetres?
Multiply L × W × H in cm and divide by 1,000,000.
How do I calculate CBM from inches?
Multiply L × W × H in inches and divide by 61,024.
How many CBM is a 20ft container?
About 33 CBM nominal, 25–28 CBM usable.
What is W/M?
Weight or measure: sea freight charges whichever is higher, tonnes or CBM.
Is the CBM Calculator free to use?
Yes. The CBM Calculator on Custom Converter is completely free, with no sign-up, no daily limit and no watermark.
Does the CBM Calculator work on mobile phones?
Yes. It is built mobile-first and works on Android phones, iPhones, tablets and computers in any modern browser, with no app to install.