Freight forwarders, shipping lines and warehouses talk in CBM (cubic metres). Before you can get a sea freight quote or book container space, you need the total carton volume in CBM. This guide explains how to calculate carton volume in CBM for a whole shipment, using our free Carton Volume Calculator.
Single carton
CBM = Length (m) × Width (m) × Height (m)
If dimensions are in cm: CBM = L × W × H ÷ 1,000,000.
Example: 60 × 40 × 35 cm = 84,000 cm³ = 0.084 CBM.
Whole shipment
Total CBM = CBM per carton × number of cartons
Example: 150 cartons × 0.084 = 12.6 CBM.
Mixed carton sizes
| Carton size (cm) | Qty | CBM each | Total CBM |
|---|---|---|---|
| 60 × 40 × 35 | 150 | 0.084 | 12.600 |
| 50 × 30 × 30 | 80 | 0.045 | 3.600 |
| 40 × 30 × 20 | 40 | 0.024 | 0.960 |
| Total | 270 | — | 17.160 |
Rounding
Use outer dimensions and round each to the nearest centimetre. Forwarders often round total CBM up to two decimals or to the next 0.5 or 1 CBM for LCL billing.
Inches to CBM
If dimensions are in inches, multiply L × W × H and divide by 61,024. Example: 24 × 16 × 14 in = 5,376 in³ = 0.088 CBM.
How forwarders use CBM
- LCL sea freight: charged per CBM or per tonne, whichever is higher; see CBM to KG Calculator.
- Container planning: a 20 ft container holds about 33 CBM internally but realistically 25 to 28 CBM of cartons.
- Warehouse storage: often charged per CBM per month.
Check your numbers
Errors in carton count or dimensions are common and costly. Double-check the packing list against cartons before booking. For a deeper look at LCL charges, read CBM and LCL shipping charges.
For reducing wasted space, read reducing empty space in cartons.
Frequently asked questions
How do I calculate CBM from cm?
Multiply length, width and height in cm and divide by 1,000,000.
What is the CBM of a 60 × 40 × 35 cm carton?
0.084 CBM.
How many CBM fit in a 20 ft container?
About 33 CBM internally, with 25 to 28 CBM usable for cartons.