An NMFC code is a 4 to 6 digit number that identifies a specific commodity in the National Motor Freight Classification manual and assigns it a freight class. Carriers use these codes to price LTL freight consistently across different shippers and lanes. For some commodities, the code fixes the class outright. For others, the class varies based on density sub-classes described within the code itself.
Why NMFC codes exist
Not all freight classifies cleanly by density alone. Some items are fragile, oddly shaped, or difficult to secure in a trailer, and a pure PCF number would misprice them. NMFC codes capture those characteristics for specific commodity types, so pricing stays consistent across every carrier that uses the NMFC system, not just one carrier's internal judgment call.
How do you actually find one?
The authoritative source is the NMFC manual, published by the NMFTA, and access requires a paid subscription. For common items, your carrier, freight broker or 3PL can usually look up the code without charging you directly. For freight without a specific listing, the density-based class from the Density Calculator applies instead.
Sub-classes within a single code
Many NMFC items have sub-classes: the assigned class changes based on density thresholds defined for that specific item, not the general 18-class scale used elsewhere on this site. Sub-class 1 might be class 70 for density above 10 PCF, while sub-class 2 might be class 100 for density between 6 and 10 PCF. Read the full item description before deciding which sub-class applies to your shipment.
What this means for your bill of lading
Include the NMFC item number and freight class on the bill of lading whenever you have them. Carriers will accept shipments without one, but providing the code gives them less reason to inspect and reclass. If your carrier uses a proprietary system instead of NMFC directly, they will map your commodity description to their internal equivalent.
Shippers who move the same commodity every week usually save the item number in their shipping software once and reuse it on every bill of lading after that. It is a small bit of upfront homework that pays off on the first reweigh, since a carrier who sees a matching, correctly formatted NMFC number on the paperwork has one less reason to open the freight and remeasure it.
Not sure which class applies?
Enter weight and dimensions to get a density-based class estimate in place of a specific NMFC lookup.