From cargo volume to mass per unit volume
This tool divides the combined packed weight by the combined occupied volume. A cargo unit is one measured package or handling unit. Quantity repeats the dimensions and per-unit weight in that row; add a row when another unit has different measurements.
- Inches to cubic feet
Volume (ft³) = length × width × height ÷ 1,728 - Centimeters to cubic meters
Volume (m³) = length × width × height ÷ 1,000,000 - Combine units
Total volume = Σ (unit volume × quantity)
Total weight = Σ (unit weight × quantity) - Calculate density
Density (lb/ft³) = total lb ÷ total ft³
Density (kg/m³) = total kg ÷ total m³
Conversion constants: 1 in = 2.54 cm; 1 ft = 0.3048 m; 1 lb = 0.45359237 kg. Therefore 1 lb/ft³ = 0.45359237 ÷ 0.3048³ kg/m³. Unit switching converts your existing entries rather than reinterpreting them. Calculations retain the converted precision; results display two decimals, with cubic meters shown to four.
For example, a 36 × 24 × 24 in package at 120 lb occupies 12 ft³. Its cargo density is 10 lb/ft³, or 160.1846337396 kg/m³ before display rounding. These are illustrative inputs, not a carrier measurement or price.
Which density band does the cargo occupy?
The following is the standard 13-band density scale published by NMFTA in its June 19, 2025 article. Each lower bound is included and each upper bound is excluded. The band is selected from the unrounded density, not the two-decimal display. Density alone does not establish an NMFC item number or every commodity's class.
| Density (lb/ft³) | Density-based class |
|---|---|
| 0 to below 1 | 400 |
| 1 to below 2 | 300 |
| 2 to below 4 | 250 |
| 4 to below 6 | 175 |
| 6 to below 8 | 125 |
| 8 to below 10 | 100 |
| 10 to below 12 | 92.5 |
| 12 to below 15 | 85 |
| 15 to below 22.5 | 70 |
| 22.5 to below 30 | 65 |
| 30 to below 35 | 60 |
| 35 to below 50 | 55 |
| 50 or more | 50 |
Scale source: NMFTA — Decoding Density, checked October 22, 2026. The constants above are exact international inch, foot and pound conversions.
Questions about cargo density
Is shipment density the average of my row densities?
No. Shipment density uses total mass divided by total volume. A large package contributes more volume than a small package, so averaging their two density figures can give a different answer.
What changes when I switch from inches to centimeters?
The dimensions convert to preserve the same physical size. The density in both unit systems stays the same apart from displayed rounding. Dimension and weight units can be switched independently.
How does the cylindrical cargo option work?
It uses the rectangular occupied envelope: greatest packed diameter × greatest packed diameter × packed height or length. It does not calculate the material volume πr²h. This makes its occupied-space basis explicit; irregular-shape classification provisions may use another basis.
Why can a displayed boundary value fall in the lower band?
A value slightly below a threshold can round up on screen. The band still uses the unrounded value. Copy result includes a higher-precision density so the displayed rounding can be checked.
Does a low density tell me the cost of shipping?
No. Cargo mass per cubic foot describes how weight relates to occupied space. This calculator has no carrier prices, accessorial charges or live rating interface.