In international air freight, chargeable weight is the core basis for calculating freight rates by airlines or freight forwarders. It doesn’t simply refer to the actual weight of the cargo, but rather follows a “take the greater” rule—that is, after comparing the cargo’s “actual weight” and “volume weight,” the larger value is used as the final weight standard for calculating freight rates.
This rule essentially balances the “weight cost” and “space cost” of air transport: Aircraft cabin space is limited. Large but lightweight cargo (such as foam products, down jackets, and large plush toys) takes up a significant amount of space. Charging solely by actual weight would seriously impact the airline’s space utilization efficiency. Conversely, heavy but lightweight cargo (such as metal parts and machine accessories) primarily consumes the cargo allowance. Therefore, chargeable weight must consider both “weight” and “volume.”
- Gross Weight (GW)
Gross weight refers to the physical weight of the goods themselves, measured directly on a scale (such as an electronic scale or floor scale). The unit is typically kilograms (kg), though pounds (lb) may also be used in some scenarios.
It is the most intuitive weight indicator. For example, if a box of goods shows 25kg on the scale, then the actual weight of the box is 25kg.
- Volumetric Weight (VW)
Volumetric weight is the equivalent weight calculated by converting the volume of the goods according to a certain standard. Its purpose is to convert the “space occupied” by the goods into a value comparable to the actual weight. Its core principle is: 1 cubic meter of space corresponds to a fixed weight. The larger the volume of the goods, the higher the converted volumetric weight.
Volumetric Weight Conversion Formula (International Standard)
The most commonly used conversion formula for international air freight is:
Volumetric Weight (kg) = Cargo Length (cm) × Width (cm) × Height (cm) ÷ Volume Conversion Factor
The volume conversion factor is a key parameter and varies slightly depending on the scenario, but there are two mainstream industry standards:
Standard Factor 5000: Applicable to most general cargo (such as general cargo, textiles, electronics, etc.) and is the most common conversion standard used by airlines worldwide.
Strict Factor 6000: Some airlines use this factor for “low-density cargo” (i.e., large, extremely lightweight cargo, such as air mattresses or home textiles before vacuum packaging). This results in a higher converted volumetric weight and correspondingly higher freight rates.
Conversion Example
Example 1 (General cargo, using Factor 5000):
A batch of clothing was packaged with dimensions of 60cm long, 50cm wide, and 40cm high, and weighed 18kg.
Volumetric weight = 60 × 50 × 40 ÷ 5000 = 120,000 ÷ 5000 = 24 kg.
Comparing the actual weight of 18 kg with the volumetric weight of 24 kg, the chargeable weight is 24 kg.
Case 2 (low-density cargo, using a factor of 6000):
A batch of foam boards is packaged with dimensions of 100 cm long, 80 cm wide, and 50 cm high, and has an actual weight of 15 kg.
Volumetric weight = 100 × 80 × 50 ÷ 6000 = 400,000 ÷ 6000 = 66.67 kg.
Comparing the actual weight of 15 kg with the volumetric weight of 66.67 kg, the chargeable weight is 66.67 kg (usually rounded up to 67 kg).
Case 3 (Heavy cargo, volumetric weight less than actual weight):
A box of metal parts has packaging dimensions of 30cm long, 20cm wide, and 15cm high, with an actual weight of 25kg.
Volumetric weight = 30 × 20 × 15 ÷ 5000 = 9000 ÷ 5000 = 1.8kg.
Comparing the actual weight of 25kg with the volumetric weight of 1.8kg, the chargeable weight is 25kg.
Summary
Simply put, chargeable weight = max(actual weight, volumetric weight)—whichever value is greater is used for freight calculation.
Actual weight is the “weighed weight,” while volumetric weight is the “calculated weight.” The two are related using the formula “length × width × height ÷ conversion factor.” The choice of conversion factor depends on the cargo type and airline regulations (5000 is generally used).
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