Freight & Transportation
Freight Class Guide: How NMFC Classification Works
Freight class drives LTL pricing and reclass charges. Here is how the four NMFC characteristics work and how to classify accurately the first time.
The short answer
Freight class is an NMFC code from 50 to 500 that determines LTL pricing, based on four characteristics: density, stowability, ease of handling, and liability. Denser, easier-to-handle, lower-risk freight gets a lower class and a lower rate.
The four characteristics
Density is pounds per cubic foot and is the dominant factor for most commodities. Stowability reflects how well the item loads with other freight — hazmat, oversized, or awkward shapes score worse. Handling covers whether special equipment or care is required. Liability covers theft appeal, perishability, and the risk the item poses to adjacent freight.
Some commodities have a fixed class in the NMFC regardless of density; others are density-based, meaning the class moves as your packaging changes. Knowing which category your product falls into is the single most useful piece of classification knowledge you can have.
Class bands at a glance
| Class | Typical density (lbs/ft³) | Example freight |
|---|---|---|
| 50–55 | 30–50+ | Bricks, nuts and bolts, dense machinery parts |
| 60–85 | 12–30 | Car parts, packaged food, appliances |
| 92.5–125 | 6–12 | Computers, boxed televisions, cabinets |
| 150–250 | 2–6 | Furniture, light fixtures, mattresses |
| 300–500 | Under 2 | Ping pong balls, kayaks, unassembled furniture |
How to calculate density correctly
- Measure the shipment as it ships — including the pallet, wrap, and any overhang.
- Multiply length x width x height in inches, divide by 1,728 to get cubic feet.
- Divide total shipment weight, including packaging, by cubic feet.
- Round dimensions up to the nearest inch; carriers do, and their dimensioner is the tie-breaker.
- Recalculate whenever packaging changes — a taller pallet at the same weight can cost you two class tiers.
Avoiding reclass and reweigh charges
Carriers run shipments through automated dimensioners and scales. If your bill of lading says class 70 and the dimensioner says class 125, you get a reclass fee plus the rate difference, often weeks later. Inspection and correction charges are one of the largest sources of freight invoice variance for mid-size shippers.
The practical fixes are unglamorous: weigh and measure every SKU configuration once and store it in your item master, print accurate dimensions on the BOL, and audit invoices against expected class monthly. Where you ship a mixed catalog, negotiate an FAK (freight all kinds) agreement that collapses a range of classes into one negotiated class — it simplifies quoting and reduces dispute volume.
What is changing
The NMFTA has been consolidating density-based classification, moving many commodities onto a standardized density scale and simplifying subcategories. The practical implication for shippers is the same either way: accurate dimensional and weight data at the item level is now the foundation of correct LTL pricing, and shippers without it will keep paying corrections.
Frequently asked questions
- What happens if I use the wrong freight class?
- The carrier reclassifies the shipment after inspection and rebills the difference plus an inspection fee. Repeated misclassification can also affect your negotiated pricing at renewal.
- What is an FAK agreement?
- Freight All Kinds is a negotiated arrangement where several classes are billed at a single agreed class. It simplifies rating for shippers with diverse catalogs, but only helps if your true class mix sits above the FAK class.
- Does freight class apply to truckload shipments?
- No. Class applies to LTL. Truckload pricing is based on lane, equipment type, weight, and market conditions.
- How do I find the NMFC code for my product?
- NMFC codes come from the NMFTA ClassIT database, which most carriers and 3PLs can look up for you. For density-based items, you also need current dimensions and weight to land on the right class.