Industry Terminology and Jargon – What are Heavy Freight, Bulk Freight, and Flat Freight?

In the logistics and transportation industry, especially when it comes to air freight and express delivery, “Heavy Freight,” “Bulk Freight,” and “Flat Freight” are core concepts that come up every day. They directly determine how your freight rates are calculated, and understanding them can help you better estimate costs and even save money.

I. Core Concept: Chargeable Weight
To understand these three terms, you must first understand the concept of “Chargeable Weight.”

Logistics companies don’t simply calculate charges based on the actual weight of the goods, but rather on the chargeable weight. The chargeable weight is the greater of the actual weight and the volumetric weight.

Why? Because transportation vehicles (aircraft, trucks) have limited carrying space (volume) and load capacity. A heavy but small item (such as a piece of iron) consumes load capacity, while a light but bulky item (such as feathers) consumes space. To ensure fair pricing, logistics companies need to strike a balance between weight and volume.

The formula for calculating volumetric weight is:
Volumetric weight (kg) = Length (cm) × Width (cm) × Height (cm) / Conversion Factor

This conversion factor is the key to distinguishing “heavy cargo,” “bulky cargo,” and “flat cargo”! This factor may vary depending on the mode of transportation, company, or even region.

II. Detailed Terminology
Typically, we use the kilograms equivalent of one cubic meter (CBM) of cargo as the standard for classification. This standard is often called the weight-to-bulk ratio.

Let’s use a common sea/air freight standard as an example (baseline: 1 CBM = 1000 kg):

1. Heavy Cargo / Deadweight Cargo
   Definition: This refers to cargo whose actual weight is greater than its volumetric weight.

Characteristics: High density, strong and heavy.

Billing Method: Freight is calculated based on actual weight.

Examples:

Molds, machinery and equipment, metal materials, building materials, books, mineral water, etc.

Calculation: A box of equipment weighs 500kg and has a volume of 0.5 CBM (i.e., 500,000 cm³).

Volumetric weight = 500,000 / 6000 ≈ 83.3kg (calculated using an air freight factor of 6000).

Actual weight (500kg) > Volumetric weight (83.3kg) → This is heavy cargo, so it will be charged as 500kg.

2. Light Cargo / Bulky Cargo / Volumetric Cargo
   Commonly known as: throw cargo, light cargo, or volumetric cargo.

Definition: This refers to cargo whose volumetric weight is greater than its actual weight.

Characteristics: Low density, light weight, and space-consuming.

Billing method: Freight is calculated based on volumetric weight. This is the least cost-effective scenario because you are paying for “air.”

Examples:

Down jackets, cotton, plastic toys, foam, cardboard boxes, furniture (such as chairs), yoga mats, etc.

Calculation: A box of down jackets weighs 50kg and has a volume of 2 CBM (i.e., 2,000,000 cubic centimeters).

Volumetric weight = 2,000,000 / 6000 ≈ 333.3kg (calculated using an air freight factor of 6000)

Volumetric weight (333.3kg) > Actual weight (50kg) → This is bulk cargo, so it will be charged as 333.3kg! The freight is over six times the actual weight!

3. Normal Cargo
   Definition: This refers to cargo whose actual weight and volumetric weight are very close to or equal.

Characteristics: This cargo achieves a “perfect balance” of weight and volume, making it ideal for logistics companies to “break even.”

Billing Method: Either actual weight or volumetric weight can be used, as they are nearly identical.

Example:

Many standard packaged goods may approach this balance point.

Calculation: A box of cargo weighs 150 kg and has a volume of 0.9 CBM (i.e., 900,000 cm³).

Volumetric weight = 900,000 / 6000 = 150 kg

Actual weight (150 kg) = Volumetric weight (150 kg) → This is flat cargo, so it will be charged as 150 kg.

III. Terminology and coefficient differences between different modes of transportation

Air freight:

Common conversion coefficients: 6000 (commonly used in North America) or 5000 (other regions).

For example: With a coefficient of 6000, 1 CBM ≈ 166.67 kg. This means:

If your cargo’s density is greater than 166.67 kg/m³, it’s heavy cargo.

If your cargo’s density is less than 166.67 kg/m³, it’s bulk cargo.

International Express (e.g., DHL, FedEx, UPS):

Common conversion factor: 5000.

This is the most stringent standard! 1 CBM ≈ 200 kg. This can easily cause your cargo to become “bulk cargo,” causing freight costs to skyrocket.

Sea Freight:

Full Container Load (FCL): Generally, there’s no distinction between heavy and bulk cargo. You pay for the entire container. As long as it’s within the weight limit (shipping companies have weight limits for containers), you can load as much bulk cargo as you want.

Less than Container Load (LCL): Usually charged by volume (CBM), but there’s an implicit weight-bulk cargo ratio: 1 CBM: 1000 kg.

That is, if one cubic meter of cargo weighs more than 1000 kg, it’s charged by weight tons; if it’s less than 1000 kg, it’s charged by volume tons per CBM.

So, for sea freight, only cargo with a density > 1000 kg/m³ is considered heavy cargo. This standard is very flexible, making sea freight the best choice for bulk cargo.

Summary and Recommendations
Terminology Core Characteristics Billing Basis Logistics Company’s Perspective
Heavy Cargo Actual Weight > Volumetric Weight Actual Weight “Great cargo, doesn’t take up space, I love shipping it!”
Bulky Cargo Volumetric Weight > Actual Weight Volumetric Weight “This annoying cargo takes up my precious space and costs me extra!”
Standard Cargo Volumetric Weight ≈ Actual Weight Either is acceptable “Standard cargo, break even, just right.”
Golden Rules for Shippers:

Calculate before shipping: Use the formula length * width * height / conversion factor to calculate the volumetric weight. Compare this to the actual weight to predict the billable weight in advance and avoid bill shocks.

Optimize Packaging: For bulky cargo, do everything you can to reduce the volume! Use compression bags, foldable packaging, and reduce unnecessary filler. Every bit of packaging reduction can save you a significant amount on shipping costs.

Choose the Right Channel: For heavy cargo, air or express delivery may be more cost-effective; for bulky cargo, prioritize ocean shipping (especially LCL), which can significantly reduce costs.

By understanding these jargons, you can better communicate with freight forwarders and make the most economical and intelligent logistics decisions.