Heavy Cargo vs Bulky Cargo: Sea, Air and Inland Chargeable-Weight Rules

For the same shipment, the freight forwarder says it should be calculated as heavy cargo, while the shipping line calculates it by volume—the problem is usually not the cargo, but that the terms “heavy cargo” and “light/bulky cargo” have been applied under two different sets of criteria: one for stowage and one for billing. This article brings together the three conversion ratios commonly used for ocean freight, air freight, and inland destinations in the destination country, and provides a reproducible method for making the determination.

1. First Distinguish the Two Bases

Stowage basis: This looks at the stowage factor: how many cubic meters each ton of cargo occupies. If the stowage factor is less than the ship's cargo volume coefficient, the cargo is heavy cargo; if greater, it is light/bulky cargo (also called light cargo or low-density cargo). This basis determines how containers are loaded and how cargo is arranged in the hold.

Billing basis: This looks at the conversion ratio: whether the carrier charges by weight or by volume depends on how many kilograms are converted per cubic meter. This basis determines how the bill is calculated. Mixing the two bases is the main reason quotations do not match.

2. Ocean LCL: 1 CBM vs. 1 Ton

The most commonly used threshold for ocean LCL is 1 CBM ≈ 1,000 kg, i.e., conversion based on the density of water: if a shipment weighs more than 1 ton per cubic meter, it is charged by weight ton; if less than 1 ton, it is charged by volume ton (the number of cubic meters). The chargeable ton is the greater of the two, which is what the industry calls W/M.

Most LCL quotations also distinguish between two sets of rates: a light-cargo rate (by volume) and a heavy-cargo rate (by weight); the unit rates for the two differ on the same route. When requesting a quote, first confirm which side your cargo falls on, and only then does it make sense to compare unit rates.

3. Air Freight: Volumetric Weight at 1:6000

The common air freight conversion is: volumetric weight (kg) = length (cm) × width (cm) × height (cm) ÷ 6000, i.e., 1 CBM equals 166.67 kg. The chargeable weight is the greater of the actual gross weight and the volumetric weight.

Some airlines or freight forwarders use coefficients such as 1:5000 or 1:4000 for specific routes (more common in air express and some regional routes). Before booking, rely on the coefficient stated in the quotation; chargeable weights calculated with different coefficients can differ considerably.

4. Inland Destinations in the Destination Country: Ratios Must Be Calculated Separately

For the same shipment, the port of origin may calculate at 1:1000, while an inland destination in the destination country may use another set of coefficients. For LCL to US inland points, 1 CBM ≈ 363 kg is commonly used because US highways have strict gross vehicle weight limits, so less weight can be allocated to the inland leg; inland points in Europe and Australia also each have their own customary ratios.

When quoting door-to-door or inland transfer, first confirm the conversion coefficient applicable to the inland leg in the destination country, then back-calculate the chargeable tons for the entire shipment. If you estimate only according to the origin-port basis, the inland leg is easily undercalculated.

5. Why Coefficients Vary by Port

The heavy/light cargo coefficient is not a fixed mathematical constant; it adjusts with the cargo-volume mix on the route, the season, and shipping line policies: when capacity is tight in peak season, carriers are more inclined to charge as heavy cargo; the ratios published for the same port in different years may also differ. Historical ratios you find can only serve as an order-of-magnitude reference; in practice, the billing rules confirmed at the time of booking shall prevail.

6. Practical Determination Steps

1. Measure the actual gross weight and volume accurately (including packaging and pallets; units kg and CBM)
2. Calculate density: gross weight ÷ volume (kg/CBM)
3. Apply the threshold for the relevant scenario: ocean LCL 1,000; air freight 166.67; US inland 363
4. If density is greater than the threshold → charge by weight; if less → charge by volume
5. When destination-country inland delivery is involved, recheck once using the coefficient for the inland leg
6. Keep weight and volume data consistent across quotation, booking, and customs declaration

Frequently Asked Questions

Is 1 ton of cargo always considered heavy cargo?

Not necessarily. The basis for judgment is density, not total weight: 1 ton packed in 0.8 cubic meters is heavy cargo, while packed in 3 cubic meters it is light/bulky cargo. Ocean LCL commonly uses 1 CBM = 1,000 kg as the threshold.

Do the chargeable tons for LCL need to match the weight and volume declared for customs?

They must match. The carrier will re-measure when receiving the cargo at the freight station and will charge based on the re-measured data; customs declaration is based on the actual gross weight and number of packages. If the difference between the two is too large, it is easy to be questioned during inspection, so measure the weight and dimensions accurately before shipment and keep them on file.

Further Reading

• Container Freight Cost Composition: Breakdown of Cost Items Under Different Handover Methods
• Weight Limit Regulations: Weight Limit Policies and Overweight Fees by Country/Shipping Line
• Points to Note for LCL: Direct Consolidation vs. Transshipment Consolidation, Documentation and Billing Essentials
• Container Dimensions and Specifications: Internal/External Dimensions and Weight Limits of 20GP/40GP/40HQ/45HQ
• Container Handover Methods: Detailed Explanation of FCL/FCL, FCL/LCL, LCL/LCL, and LCL/FCL

Data Note: The conversion factors in this article are commonly used industry values. Individual shipping lines, airlines, and destination-country inland carriers may have other regulations; actual charges shall be subject to the rules confirmed at the time of booking.

Not sure which basis your cargo will be charged by? Send the gross weight, volume, and destination port to Bofeng Logistics, and we will verify the chargeable tonnage for you according to the route rules.Submit an inquiry online

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Content verified in October 2026