Freight Density Converter: pcf to kg/m³ and the Class It Lands In

1 lb/ft³ (pcf) = 16.018463 kg/m³. Multiply pcf by 16.018463 to get kg/m³; divide kg/m³ by 16.018463 to get pcf. The class still comes from the pcf number, because the density bands are published in lb/ft³.

Convert it by hand, in inches or in centimetres

1. Measure length, width and height to the farthest points, pallet and overhang included.
2. Multiply the three numbers to get a volume in cubic inches, or in cubic centimetres if you measured in cm.
3. Turn that volume into cubic feet: divide cubic inches by 1,728, or divide cubic centimetres by 28,316.8466.
4. Divide the total weight by the cubic feet. In pounds this is already lb/ft³. If the weight is in kilograms, multiply it by 2.20462262 first, because the density bands are published in pounds.
5. Multiply the pcf figure by 16.018463 if you need kg/m³ for a metric document or a customs form.

Imperial example: 48 × 40 × 48 in is 92,160 in³, which is 53.33 ft³. At 900 lb the density is 16.88 pcf, or 270.3 kg/m³, which is Class 70.

Metric example: 122 × 102 × 122 cm is 1,518,168 cm³, which is 53.62 ft³. At 408 kg (899.5 lb) the density is 16.78 pcf, or 268.7 kg/m³, which is Class 70.

Rounding the cube moves the number

Take the same 900 lb load and divide it by a rounded and an unrounded cube: 53.33 ft³ gives 16.88 pcf, 53 ft³ gives 16.98 pcf, and 54 ft³ gives 16.67 pcf. All three sit inside the 15 to under 22.5 lb/ft³ band, so the class does not move. Near a band edge it does: the next band starts at 12 lb/ft³, so any rounding step that carries the number across 12 changes the class that goes on the paperwork. Convert first, then round, and write down which cube you rounded to.

Download the conversion and band table

The file below is the whole table in CSV: every band boundary in lb/ft³ and in kg/m³, the class each band maps to, and both conversion factors. Open it in Excel or Sheets and keep it with the shipping paperwork.

The bands this converter reads

Source: NMFTA, “Decoding Density: The Freight Factor You Can’t Afford to Overlook”, posted June 19, 2025, which lists the 13-subprovision standard density scale (Sub 1 to Sub 13); cross-checked against NMFTA, “How Much Density Margin Does Your Packaging Need?”, posted October 22, 2026, which repeats the 6, 8, 10, 12, 15 and 22.5 lb/ft³ thresholds as Class 125, 100, 92.5, 85, 70 and 65. The conversion factors are exact SI definitions: 1 lb = 0.45359237 kg and 1 in = 2.54 cm, so 1 lb/ft³ = 16.01846337 kg/m³. Density sets class only for density-based NMFC items; the item number and its provisions still decide the class.

Who this converter does not fit

• Multi-piece shipments. Add every piece’s volume and every piece’s weight before dividing. Converting or rounding each piece separately gives a different number than one shipment.
• Metric-only measurements. Switch the length unit to centimetres and the weight unit to kilograms above; do not convert the class band itself, because the band edges only exist in lb/ft³.
• Pallet and packaging weight. The weight field is the gross weight of the handling unit, pallet included. Weighing the cartons alone understates density and can move the class down.
• Carrier reweigh and re-dimension. This page reproduces your own measurement, not the carrier’s. If the carrier measures differently, its figure is the one that gets invoiced.
• Item lookup. A density does not name an NMFC item. If you need the item number, start from the NMFC freight class lookup.