The CBM Formula in Centimeters
CBM (Cubic Meter, or m³) is the standard volume unit in international freight. Since most Asian supplier packing lists use centimeters, knowing how to convert directly from cm to CBM is a core skill for any freight professional or importer.
The formula works because 1 meter = 100 centimeters, meaning 1 cubic meter = 100 × 100 × 100 = 1,000,000 cubic centimeters. So when you multiply three centimeter dimensions together, you get the volume in cm³. Divide by 1,000,000 to convert to m³ (CBM).
CBM = (L cm × W cm × H cm) ÷ 1,000,000
Method 2 — Convert to meters first:
CBM = (L ÷ 100) × (W ÷ 100) × (H ÷ 100)
Both methods give identical results. Method 1 is faster on a calculator.
Step-by-Step Process
- Measure each carton's outer dimensions: length, width, and height in centimeters.
- Multiply: L × W × H to get the volume in cm³.
- Divide the result by 1,000,000 to get CBM per carton.
- Multiply CBM per carton by the total quantity of cartons.
Worked Example — Single Carton
A standard garment export carton measuring 50 cm × 40 cm × 30 cm:
60,000 ÷ 1,000,000 = 0.06 CBM per carton
At an LCL rate of $50 per W/M ton and a shipment weight of 15 kg per carton, a single carton weighing 0.015 tons would be charged on CBM (0.06 > 0.015), costing $3.00 in ocean freight for that one carton. Scale this by your total quantity to estimate the freight component of your LCL shipment.
Worked Example — Multiple Products (Packing List)
A packing list with three different SKUs:
| Product | L × W × H (cm) | Qty | CBM / carton | Total CBM |
|---|---|---|---|---|
| T-shirts | 55 × 40 × 35 | 20 | 0.077 | 1.540 |
| Shoes | 60 × 35 × 30 | 15 | 0.063 | 0.945 |
| Accessories | 40 × 30 × 25 | 30 | 0.030 | 0.900 |
| Total Shipment CBM | 3.385 CBM | |||
This 3.385 CBM shipment would be quoted as an LCL shipment. The freight forwarder compares 3.385 CBM against the total weight divided by 1,000 to determine the W/M ton count for billing.
Quick Reference: CBM for Common Carton Sizes
Common export carton dimensions and their CBM values:
| L × W × H (cm) | CBM per unit | CBM for 50 units | CBM for 200 units |
|---|---|---|---|
| 30 × 20 × 20 | 0.012 | 0.60 | 2.40 |
| 40 × 30 × 25 | 0.030 | 1.50 | 6.00 |
| 50 × 40 × 30 | 0.060 | 3.00 | 12.00 |
| 55 × 40 × 35 | 0.077 | 3.85 | 15.40 |
| 60 × 50 × 40 | 0.120 | 6.00 | 24.00 |
| 70 × 50 × 50 | 0.175 | 8.75 | 35.00 |
| 80 × 60 × 60 | 0.288 | 14.40 | 57.60 |
| 100 × 80 × 80 | 0.640 | 32.00 | 128.00 |
Converting CBM to Volumetric Weight
Once you have your total CBM, the next step is comparing it to the actual weight of your cargo. This determines which basis you pay freight on.
For ocean LCL freight: compare total CBM against total weight (kg) ÷ 1,000. The higher figure is your chargeable W/M tons.
For air freight: multiply total CBM by 6,000 to get volumetric weight in kg. If that exceeds actual weight, you pay the volumetric rate.
See our guide on CBM for air freight for a full walkthrough of the 6,000 divisor and IATA standards, or read 1 CBM = how many kg to understand the ocean vs air conversion difference.
Once you know your CBM and weight, use our Chargeable Weight Calculator to compare both modes and see exactly what you will be billed for.
No conversion needed. Select "cm" from the unit dropdown and enter your carton dimensions.
Open CBM Calculator →