How do I calculate freight density?

Multiply length × width × height in inches, divide by 1,728 for cubic feet, and divide the weight in pounds by that. In metric, divide kilograms by cubic metres. A 48 × 40 × 45 in pallet of 450 lb is 9 lb/ft³.

How do I convert lb/ft³ to kg/m³?

Multiply by 16.018. A pound is exactly 0.45359237 kg and a cubic foot 0.0283168 m³, so 9 lb/ft³ is about 144.2 kg/m³.

Why does freight density matter?

It sets the estimated NMFC class for US LTL freight, and decides whether a carrier bills on actual or volumetric weight — by air, freight lighter than 166.7 kg/m³ is billed on its volume.

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Freight Density Calculator

Work out a shipment's density in lb/ft³ and kg/m³ from its size, including overhang, and its weight — then carry it straight into the freight class calculator.

Your shipment

Length, including overhang

Width, including overhang

Height

Number of pieces

Total weight

Density

9lb/ft³

Density: 144.2kg/m³
Total volume: 50ft³
Weight per piece: 450lb

Measured at the outermost points, overhang included — the way a carrier will measure it.

Estimate the freight class for this shipment →

The formula

Density (lb/ft³) = weight (lb) ÷ (length × width × height in inches ÷ 1,728) · Density (kg/m³) = weight (kg) ÷ volume (m³)

1 lb/ft³ = 16.018 kg/m³, since a pound is exactly 0.45359237 kg and a foot exactly 0.3048 m.

Worked example

NMFTA's example, and the calculator's opening values: a 48 × 40 × 45 in pallet weighing 450 lb is 86,400 in³ ÷ 1,728 = 50 ft³, so its density is 450 ÷ 50 = 9 lb/ft³ — about 144.2 kg/m³. On the NMFC's 2025 density scale that is class 100.

What density decides

US less-than-truckload: the freight class, for every NMFC item classed by density.
Air cargo: whether you pay on volume. At IATA's 6,000 cm³ per kg, freight under 166.7 kg/m³ is billed on volumetric weight.
Road part loads: the same test at the carrier's factor — 333 kg/m³ for Posti, 250 for Schenker in Germany.

When the answer misleads

When the measurements are not the carrier's. NMFTA's method measures length, width and height at the outermost points, every overhang and projection included; a pallet measured at its deck, not its load, reads denser than the carrier will find it. And density estimates a class — the NMFC item decides it.

FAQ

Freight Density Calculator: common questions

How do I calculate freight density?: Multiply length × width × height in inches, divide by 1,728 for cubic feet, and divide the weight in pounds by that. In metric, divide kilograms by cubic metres. A 48 × 40 × 45 in pallet of 450 lb is 9 lb/ft³.
How do I convert lb/ft³ to kg/m³?: Multiply by 16.018. A pound is exactly 0.45359237 kg and a cubic foot 0.0283168 m³, so 9 lb/ft³ is about 144.2 kg/m³.
Why does freight density matter?: It sets the estimated NMFC class for US LTL freight, and decides whether a carrier bills on actual or volumetric weight — by air, freight lighter than 166.7 kg/m³ is billed on its volume.