Understanding the Difference Between Cubic (Volumetric) Weight and Deadweight
When shipping goods, many clients are surprised to find that freight costs aren’t solely determined by how much an item weighs on a scale. Instead, carriers often use two types of weight to calculate freight charges: cubic weight (also known as volumetric weight) and deadweight (actual weight).
Understanding the difference between these two concepts is crucial for managing shipping costs effectively.
What is Deadweight (Actual Weight)?
Deadweight is the most straightforward concept—it refers to the actual weight of the item as measured on a scale. For example, if you’re shipping a box of books that weighs 10 kilograms, the deadweight is simply 10 kg.
Deadweight is used when the shipment is heavy and dense relative to its size. In such cases, the item’s size doesn’t significantly affect how much space it takes up in a truck, plane, or shipping container.
What is Cubic or Volumetric Weight?
Cubic weight, on the other hand, considers the amount of space a package occupies. Carriers use a formula to convert the volume (length × width × height) into a weight equivalent to account for low-density items that take up a lot of room but weigh very little.
The formula for calculating cubic weight can vary by carrier:
- Cubic Weight (kg) = (Length × Width × Height in cm) / 5000
- (Some carriers may use 4000, 6000, or other divisors depending on mode of transport and service level.)
So, for a large box measuring 100 cm × 50 cm × 40 cm, the cubic weight would be:
- (100 × 50 × 40) / 5000 = 40 kg
Even if the actual (deadweight) of that box is only 10 kg, the carrier will charge based on the greater of the two weights.
If you would like to calculate the Cubic/Volumetric weight of a carton, you can use this handy Volumetric Weight Calculator.
Why Do Carriers Use Both?
Freight companies, especially air and express carriers, need to maximize space as well as weight in their vehicles. A truck or airplane may “fill up” long before it reaches its weight limit if it carries bulky but light items, such as pillows or plastic containers. To prevent losing money on large, low-weight shipments, carriers use cubic weight to reflect the space a shipment occupies.
Therefore, freight is charged based on whichever is higher:
- Deadweight (actual weight), or
- Cubic weight (space it takes up)
This approach ensures carriers are compensated fairly for both heavy and bulky goods.
How This Affects Shippers
Understanding this principle is vital for businesses and individuals sending freight. Packaging inefficiencies—such as using oversized boxes or including too much empty space—can lead to significantly higher shipping costs due to increased cubic weight.
To reduce costs:
- Use packaging that fits the product closely
- Consider vacuum-packing or compressible materials
- Understand your carrier’s specific volumetric divisor and policies
- If your products are bulkier, look for a 3PL warehouse that offers Deadweight only rates
Conclusion
Understanding how the weight of your product is calculated by your Carrier is fundamental to managing your freight costs. While deadweight measures physical mass, cubic weight accounts for volume. The majority of Carriers use whichever is greater to determine charges, making efficient packaging and awareness of dimensional weight rules essential for cost-effective shipping.
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