How our calculators work

Freight class — the NMFC density scale

Freight class starts with density: weight in pounds divided by volume in cubic feet. We map that density to the standard 18-class scale in the National Motor Freight Classification (NMFC), published by the National Motor Freight Traffic Association (NMFTA). Denser freight rates a lower class and ships cheaper; lighter, bulkier freight rates higher. See the full breakpoints on the freight class chart.

One caveat we make explicit everywhere: some commodities carry a fixed NMFC item number that overrides density. Our tool gives the accurate density-based estimate and tells you to confirm the exact NMFC item with your carrier — because that number drives real billing.

Dimensional & chargeable weight

Carriers bill the greater of actual and dimensional weight, because trailer and aircraft space runs out before weight does. Dimensional weight = (length × width × height) ÷ a dimensional divisor. We use the standard divisors — 139 and 166 in³/lb for domestic parcel, 5000 and 6000 cm³/kg for air freight — and let you pick the one your carrier quotes. Try the dimensional weight calculator.

CBM & volumetric weight

Cubic metres (CBM) = length × width × height in metres. For ocean LCL, one CBM is treated as a 1,000 kg revenue ton; for air freight, volumetric weight uses roughly 167 kg per cubic metre (the same 6000 cm³/kg standard). The CBM calculator reports both alongside container fit.

Pallets & containers

Pallet and container math is geometric. We use real footprints — the GMA pallet at 48 × 40 in and the Euro pallet at 1200 × 800 mm — and standard internal dimensions for 20 ft, 40 ft and 40 ft High Cube containers. Fit is a best-orientation estimate: it finds how many uniform units pack in, but does not model weight limits, load bracing, or mixed stacking. Treat the count as a ceiling and confirm a real load plan with your carrier.

Accuracy & limits

These are planning estimates, and we say so on every result for a reason: your carrier sets the final freight class, NMFC item number and chargeable weight. The fundamentals here — the density scale, the divisors, the container and pallet specs — are industry-standard and verified, but the official numbers on your bill of lading come from your carrier or broker. Always confirm before you book.