Freight Class & NMFC Codes: The 2025 Density Guide

What freight class is — and why it decides your bill

Every LTL shipment gets a class from 50 (dense, cheap) to 500 (light, bulky, expensive). That single number is the biggest lever on your rate: a one-class error can swing the cost of a line by 30% to 80%. Class isn’t a carrier’s opinion — it’s set by a national standard from the NMFTA and, for most freight, comes straight out of the density math.

How class is calculated: the density math

Multiply length, width, and height in inches, divide by 1,728 to get cubic feet, then divide the weight by that volume. The result is density in pounds per cubic foot (PCF), and PCF maps to a class on the NMFTA scale. Denser freight earns a lower class; the lighter it is for its size, the higher it climbs.

Class isn’t a guess — it’s arithmetic. If you know the density, you know the class.

The Freight Density Calculator does this for a single pallet, and the Target Class Calculator runs it backward — telling you the weight that would land a pallet in the class you’re aiming for. Prefer to look it up? The density-to-freight-class chart lists every class and its PCF range. New to the unit itself? See what PCF (pounds per cubic foot) means and how to convert it.

What changed in 2025 (and why it matters more now)

On July 19, 2025, the NMFTA began moving roughly 2,000 commodities from commodity-based to density-based classification — the most sweeping revision to freight class in years, with further dockets rolling through 2026. The practical upshot for a shipping desk: for most freight, class now rides on your weights and dimensions, not a fixed commodity code. Sloppy measurements used to cost you sometimes. Now they cost you every time. The full rundown of the 2025 NMFC density changes — timeline, impact, and how to prepare →

The multi-pallet trap most calculators miss

A shipment with several different pallets on one BOL line isn’t rated pallet-by-pallet, and carriers don’t average the classes. They rate the line by its aggregate density — total weight of every unit divided by total volume, calculated once. Class each pallet on its own and you’ll hand the carrier a number that doesn’t match the bill. This is the single most common way a “correct” class still gets reclassed. The Multi-Pallet Freight Class tool rates the whole shipment the way the carrier actually does. See a worked example in freight class for multiple pallets.

Why freight gets reclassed — and how to stop it

A carrier reclasses when a terminal inspection finds the declared class, weight, or dimensions don’t match what was measured. Most reclass events trace back to three things: underdeclared dimensions (a pallet declared 48×40×48 that arrives 48×42×60), miscalculated density, or a vague product description that maps to a different NMFC item. Reweighs work the same way — a calibrated terminal scale finds the weight off by more than the carrier’s tolerance (commonly ~200 lbs or 5%), and the line gets re-rated with an inspection fee on top.

The defense is boring and it works: measure to the farthest points on a certified scale before pickup, calculate the density (don’t eyeball the class), write a specific commodity description on the BOL, and flag every accessorial. If you captured real numbers, you can dispute a terminal reclass with documentation. If you estimated, you have nothing to stand on. See the full breakdown of why freight gets reclassed — and how to dispute a W&I back-bill →

Freight class by commodity

Class always comes down to your shipment’s own density, but it helps to know the typical range for what you ship. These guides give the usual class band, the density math, and a worked example for common commodities: furniture, mattresses, appliances, electronics, clothing, tires, auto parts, lumber, and steel. They span the scale — dense steel and lumber sit near class 50–70, while light-and-bulky mattresses and furniture climb toward class 250–400.