Calculating CBM (cubic meters) is the core skill every importer must master, because it determines your sea-freight cost and helps you pick the right container. Many importers are surprised by high shipping invoices simply because they never measured their shipment volume accurately. In this guide from MESAMA, we walk you through how to calculate your shipment's CBM step by step.
What is CBM?
CBM (Cubic Meter) is the unit used to measure a shipment's volume in cubic meters. Carriers rely on it to price shipments, especially in LCL (less-than-container load), which is charged per cubic meter.
The CBM formula
The formula is simple:
Carton CBM = (length × width × height in centimeters) ÷ 1,000,000
then:
Total CBM = carton CBM × number of cartons
We divide by one million because one cubic meter = 100 cm × 100 cm × 100 cm = 1,000,000 cm³.
💡 Don't want to do it by hand? Use MESAMA's free CBM calculator to work out your shipment volume and the right number of containers instantly.
Worked example
Suppose you have 100 cartons, each measuring 40 × 30 × 30 cm:
| Step | Calculation | Result |
|---|---|---|
| Carton volume | 40 × 30 × 30 | 36,000 cm³ |
| Carton CBM | 36,000 ÷ 1,000,000 | 0.036 m³ |
| Total CBM | 0.036 × 100 | 3.6 m³ |
So your shipment is 3.6 cubic meters — a perfect fit for LCL (less-than-container load).
How CBM determines container choice
| Container | Approx. capacity |
|---|---|
| 20ft | ~28 m³ |
| 40ft | ~58 m³ |
If your total CBM is close to a container's capacity, a full container load (FCL) is usually cheaper. For smaller quantities, LCL is the better fit.
Volumetric weight: an important variable
In air freight specifically, the cost is charged on the greater of the actual weight and the volumetric weight. So large, lightweight goods may be priced by their volume rather than their weight.
Calculate your shipment's CBM instantly
Instead of manual math, use MESAMA's free CBM calculator: enter the dimensions, carton count, and weight to instantly see total CBM, total weight, container fill ratio, and which container suits you.
Need help estimating your shipping cost? Contact MESAMA for an accurate freight quote, or read about the difference between FCL and LCL.