Freight Class for Auto Parts
Auto Parts cover a huge density range, but boxed metal parts are dense, so under the 2025 density-based scale most land in the class 65 to 110 range. Light, bulky body panels class higher. Here’s the typical range, the math, and the exact class one click away.
The short answer
Typical packaged auto parts runs about 8–23 PCF, which maps to roughly class 65–100 on the 2025 NMFTA scale. Worked example — a boxed alternator carton, 24×18×18 in at 65 lb:
24×18×18 ÷ 1,728 = 4.5 ft³ → 65 ÷ 4.5 = 14.44 PCF → Class 85
Why auto parts classes the way it does
“Auto parts” is not one class — it is a category that runs from a dense, boxed engine block to a hollow plastic bumper cover. On the 2025 NMFTA scale, which rates on density (pounds per cubic foot), the compact metal parts most shops ship land in the lower-middle classes where rates are moderate.
Dense, boxed hard parts — alternators, brake rotors, pumps, castings — pack a lot of weight into a small carton and can reach class 65–77.5. Larger or lighter parts like exhaust assemblies or boxed panels carry more air and drift toward class 100–110. Big, air-filled body panels and bumpers can class much higher — so calculate each carton from its real weight and dimensions.
How to calculate it for your shipment
Multiply your packed length, width, and height in inches, divide by 1,728 to get cubic feet, then divide the weight by that volume for density in pounds per cubic foot (PCF). Map the PCF to the class on the NMFTA scale. The Freight Density Calculator does it in one step; the Target Class Calculator runs it backward to find the weight that would hit a class you’re aiming for. Prefer a lookup? The density-to-freight-class chart lists every class and its PCF band.
Get the class right the first time
Because the 2025 scale rates on density, sloppy dimensions are what get auto parts reclassed and back-billed. Measure to the farthest points on the packed piece, weigh it on a certified scale, and calculate the density before pickup — don’t eyeball the class. For the full picture of how density-based classification works, start with the freight class guide, and see why freight gets reclassed if a carrier disputes your number. Freight class is set by the NMFTA; look up your specific NMFC item with the NMFTA.
Frequently asked
What is the freight class for auto parts?
It depends heavily on the part. Compact, boxed metal parts fall between class 65 and class 100 under the 2025 density-based scale. A boxed alternator at about 14.4 PCF classes at 85, for example. Light, bulky body panels and bumpers class much higher. Calculate the exact class per carton from its weight and dimensions.
Why do body panels class so much higher than engine parts?
Density. A stamped or molded body panel is mostly shape and air, so it takes up a lot of cube for little weight and classes high. A boxed engine or brake part is compact and heavy, so it is dense and classes low. The same shipment can span several classes.
Can I ship mixed auto parts as one class?
An LTL shipment is generally classed on the overall density of the handling unit, but mixed cartons of very different density can be rated by their individual classes. For an accurate quote, calculate the density of each carton or the combined pallet rather than assuming one class.
How do I calculate freight class for auto parts?
Multiply the carton length, width, and height in inches and divide by 1,728 for cubic feet. Divide the weight in pounds by that volume to get density in pounds per cubic foot (PCF), then map the PCF to a class on the NMFTA scale. The Freight Density Calculator does it for you.