In international air freight, two shipments with identical weight can incur dramatically different transportation costs. This discrepancy stems from whether cargo is classified as "volumetric" (lightweight) or "dense" (heavyweight). Airlines don't simply charge by weight but follow a "chargeable weight" principle that considers both mass and space utilization.
Understanding Volumetric vs. Dense Cargo
The aviation industry calculates freight charges based on whichever is greater between a shipment's actual weight and its volumetric weight—a measurement reflecting space occupation.
- Volumetric weight formula: Length (cm) × Width (cm) × Height (cm) ÷ 6000 = Volumetric weight (kg)
- Dense cargo: When actual gross weight exceeds volumetric weight. These high-density items occupy relatively little space—typical examples include metal components, machinery, and hardware.
- Volumetric cargo: When volumetric weight surpasses actual weight. These low-density goods consume disproportionate space—common examples being plastic products, foam materials, oversized plush toys, and cushioned household items.
The Chargeable Weight Principle
Airlines apply a "greater of" rule—comparing actual and volumetric weights—then use the higher value to determine charges. This chargeable weight directly impacts final shipping costs.
Pricing Structures
Dense cargo pricing: Airlines use actual weight multiplied by applicable rates (General Cargo Rate or Specific Commodity Rate). For example, 100kg of hardware with 60kg volumetric weight would incur charges based on 100kg.
Volumetric cargo pricing: Charges apply to volumetric weight to compensate for lost cargo space. A 20kg plush toy with 80kg volumetric weight would pay for 80kg.
Additional Fees for Oversized Volumetric Items
Exceptionally large volumetric shipments may incur surcharges—such as oversized or overlength fees—due to handling complexities and specialized storage requirements. Dense cargo typically avoids these extras unless exceeding standard size/weight limits.
Hybrid Calculation for Intermediate-Density Goods
Some carriers implement tiered rates for cargo falling between clear volumetric/dense classifications, though still adhering to the fundamental "greater of" principle when determining chargeable weight.
Understanding these distinctions enables shippers to optimize packaging and logistics strategies. Precise measurements and consultations with freight specialists before shipment can yield significant cost efficiencies.