How to Calculate CBM (Cubic Meters) – A Step-by-Step Guide for Shipping

In the field of international freight transportation, the term CBM (Cubic Meter)—also known as cubic volume—is widely recognized. It is a standard unit used to measure the volume of cargo, allowing shipping costs to be calculated based on dimensions rather than just weight. This article will help you understand CBM conversion, how to calculate CBM for different modes of transport, and introduce effective tools for volume conversion.

What is CBM (Cubic Meter) in Shipping?

CBM stands for Cubic Meter, the international unit of measurement for cargo volume. In logistics, CBM is used to determine the space a shipment occupies in a container, an aircraft hold, or a truck. In practice, many people confuse weight and volume, leading to incorrect dimension conversions and unexpected extra shipping costs.

For example: A package measuring 1m x 1m x 1m =1 CBM. If you have 10 such packages, the total volume is 10 CBM. However, if you're not familiar with how to calculate CBM for sea freight, air freight, or LCL shipments, you may receive inaccurate freight charges—resulting in unnecessary financial losses.

What Is the Formula to Calculate CBM?

Explanation:

• Length, Width, and Height refer to the dimensions of the cargo.

• Always ensure that the measurements include packaging and pallets.

• Units must be consistent—either in meters (m) or centimeters (cm).

2.1. If dimensions are measured in meters (m):

CBM = Length (m) × Width (m) × Height (m)

Example: A package with dimensions 1.2m × 0.8m × 0.6m

→ CBM = 1.2 × 0.8 × 0.6 = 0.576 CBM

2.2. If dimensions are measured in centimeters (cm):

CBM = (Length × Width × Height) / 1,000,000

Example: A package with dimensions 120cm × 80cm × 60cm

→ CBM = (120 × 80 × 60) / 1,000,000 = 0.576 CBM

This formula is especially important when using CBM calculation for LCL shipments or CBM calculation for air freight, as most air cargo and smaller shipments are measured in centimeters.

Important Notes for Accurate CBM Calculation

• Always include packaging and pallets in your measurements.

• If you have multiple identical packages: Total CBM = CBM of one package × Number of packages

• If your cargo consists of packages with different dimensions: Calculate the CBM of each item separately, then add them up for the total CBM.

CBM to KG Conversion Rate & Freight Cost Calculation Rules

The CBM to KG conversion rate is not fixed—it depends on the mode of transportation. Below are the standard volumetric weight conversion constants commonly used for each shipping method.

In practice, each shipment will have both a Gross Weight (actual weight) and a Volumetric Weight (based on dimensions). The carrier will compare these two values and use the greater one as the chargeable weight to calculate the shipping cost.

Examples:

• If the gross weight is 1,000 kg and the volumetric weight is 800 kg → the freight charge will be based on 1,000 kg.

• If the gross weight is 300 kg and the volumetric weight is 500 kg → the freight charge will be based on 500 kg.

Conclusion: When comparing the volumetric weight and the actual (gross) weight of a shipment, the higher value will be used as the basis for calculating freight charges.

Examples of How to Calculate CBM for Different Shipping Methods

CBM Calculation for Sea Freight

Notes when calculating CBM for sea shipments:

• For FCL (Full Container Load) shipments, you typically do not need to calculate CBM, as you pay a flat rate for the full container (20ft, 40ft).

• For LCL (Less than Container Load) shipments, you must calculate the exact CBM to determine the freight cost based on volume.

Example:

Number of packages: 6

Dimensions per package: 110cm x 90cm x 140cm

Weight per package: 700 kg

Step 1: Calculate total gross weight: 6 x 700kg = 4.200 kg

Step 2: Calculate CBM per package

CBM per package = (110cm x 90cm x 140cm) / 1,000,000 = 1.386 CBM

Total CBM: 6 x 1.386 CBM = 8.316 CBM

Step 3: Calculate volumetric weight

→ Sea freight conversion rate: 1 CBM = 1,000 kg

→ Volumetric weight = 8.316 × 1,000 = 8,316 kg

Step 4: Compare and determine chargeable weight

Gross weight: 4.200 kg

Volumetric weight: 8.316 kg

→ Charge based on volumetric weight: 1,513.44 kg

CBM Calculation for Road Transport

Example:

Number of packages: 5

Dimensions per package: 125cm x 100cm x 145cm

Weight per package: 650 kg

Step 1: Calculate total gross weight: 5 x 650kg = 3.250 kg

Step 2: Calculate CBM per package

CBM per package = (125cm x 100cm x 145cm) / 1,000,000 = 1.8125

Total CBM = 5 x 1.8125 CBM = 9.0625 CBM

Step 3: Calculate volumetric weight

→ Air freight conversion rate: 1 CBM = 167 kg

→ Volumetric weight = 9.0625 × 167 = 1,513.44 kg

Step 4: Compare and determine chargeable weight

• Gross weight = 3,250 kg

• Volumetric weight = 1,513.44 kg

BM Calculation for Road Freight

Example:

• Number of packages: 3

• Dimensions per package: 140cm × 100cm × 130cm

• Weight per package: 450 kg

  
  

Step 1: Calculate total gross weight→ 3 × 450 kg = 1,350 kg

Step 2: Calculate volume per package (CBM)→ (140 × 100 × 130) / 1,000,000 = 1.82 CBM→ Total CBM = 3 × 1.82 = 5.46 CBM

Step 3: Calculate volumetric weight→ Road freight conversion rate: 1 CBM = 333 kg→ Volumetric weight = 5.46 × 333 = 1,817.18 kg

Step 4: Compare and determine chargeable weight

• Gross weight = 1,350 kg

• Volumetric weight = 1,817.18 kg