A freight class calculator finds your LTL freight class by dividing the shipment’s weight by its volume in cubic feet, then matching that density (pounds per cubic foot) to the NMFC density scale. Since NMFTA Docket 2025-1 took effect on July 19, 2025, that scale has 13 density brackets, running from class 400 for freight under 1 pound per cubic foot to class 50 for freight at 50 pounds per cubic foot or more.
This guide shows the exact formula, the current 13-bracket table, three worked examples and the measuring rules that keep a calculated class from being changed at the carrier’s terminal. It also covers the cases where density alone doesn’t decide the class.
Table of Contents
- How does a freight class calculator work?
- What is the current NMFC density scale?
- How do you calculate freight class step by step?
- What do real freight class calculations look like?
- How do you measure a pallet for a freight class calculator?
- When is a calculated freight class wrong?
- How do you use your freight class once you have it?
- Frequently Asked Questions
- Sources
How does a freight class calculator work?
Every freight class calculator runs the same three-step math. It multiplies length, width and height in inches to get cubic inches, divides by 1,728 to convert to cubic feet, and divides the total weight by the cubic feet to get density. The density then lands in one bracket of the National Motor Freight Classification (NMFC) density scale, and that bracket’s class is the result.
The NMFC is published by the National Motor Freight Traffic Association (NMFTA) and lists 18 classes, from 50 to 500. Lower classes cover dense, compact freight that is cheap to move per pound; higher classes cover light, bulky or fragile freight that takes up trailer space. Beyond density, the NMFC weighs three other transportation characteristics: stowability, ease of handling and liability. Most general commodities are now rated by density, which is why the calculator is the starting point for most shippers.
What is the current NMFC density scale?
NMFTA Docket 2025-1 replaced the old 11-bracket density scale with a standard 13-subprovision scale and added classes 50 and 55 for the densest freight. The table below is the scale NMFTA adopted in its Disposition Bulletin 1371 for Docket 2025-1, effective July 19, 2025.
| Sub | Density (pounds per cubic foot) | Freight class |
|---|---|---|
| 1 | Less than 1 | 400 |
| 2 | 1 but less than 2 | 300 |
| 3 | 2 but less than 4 | 250 |
| 4 | 4 but less than 6 | 175 |
| 5 | 6 but less than 8 | 125 |
| 6 | 8 but less than 10 | 100 |
| 7 | 10 but less than 12 | 92.5 |
| 8 | 12 but less than 15 | 85 |
| 9 | 15 but less than 22.5 | 70 |
| 10 | 22.5 but less than 30 | 65 |
| 11 | 30 but less than 35 | 60 |
| 12 | 35 but less than 50 | 55 |
| 13 | 50 or greater | 50 |
Two things changed for shippers. Very dense freight that used to top out at class 60 can now rate as class 55 or 50. And because NMFTA consolidated many commodity-specific items into density-based ones, a class copied from an old bill of lading may no longer be right. Our LTL class chart lists typical commodities for each class if you want to sanity-check a result.
How do you calculate freight class step by step?
You can run a freight class calculator by hand in five steps. Use the loaded handling unit, meaning the pallet or crate with the freight on it, not the bare product.
- Measure the length, width and height of the loaded unit in inches, rounding each up to the next whole inch.
- Multiply length × width × height to get cubic inches.
- Divide by 1,728 (the cubic inches in a cubic foot) to get cubic feet.
- Divide the total weight in pounds, including the pallet and packaging, by the cubic feet. The result is density in pounds per cubic foot (PCF).
- Match the density to the 13-bracket table above to read the freight class.
For a shipment of several pallets of the same commodity, add up the total weight and total cubic feet of all units before dividing. If the units hold different commodities, calculate each one on its own, because each may carry its own NMFC item and class.
What do real freight class calculations look like?
Here are three common 48 × 40 inch pallets run through the formula. The pallet footprint is the U.S. standard, and the weights include the pallet itself.
| Loaded pallet | Cubic feet | Density (PCF) | Freight class |
|---|---|---|---|
| 48 × 40 × 40 in, 1,200 lb (boxed hardware) | 44.44 | 27.0 | 65 |
| 48 × 40 × 48 in, 500 lb (cased goods) | 53.33 | 9.4 | 100 |
| 48 × 40 × 60 in, 250 lb (light, bulky cartons) | 66.67 | 3.75 | 250 |
The first pallet works out as 48 × 40 × 40 = 76,800 cubic inches, divided by 1,728 = 44.44 cubic feet, and 1,200 ÷ 44.44 = 27.0 PCF, which falls in the 22.5-to-30 bracket for class 65. The third pallet shows how quickly height raises the class: the same footprint stacked 60 inches tall with light cartons drops to 3.75 PCF and class 250.
Small changes near a bracket edge matter. A pallet at 9.8 PCF rates class 100, but trimming a few inches of empty height to push it past 10 PCF moves it to class 92.5. Removing dead space is often the cheapest way to improve a class.
How do you measure a pallet for a freight class calculator?
Carriers check declared dimensions and weight at their terminals, and a mismatch leads to a reclassification or reweigh correction on the invoice. Measuring the way the carrier does prevents that.
- Measure at the widest points. Include any product or carton overhang beyond the pallet edges.
- Measure height from the floor. The pallet’s own height (often about 5 to 6 inches) counts.
- Round up every dimension to the next full inch.
- Weigh the full unit, including the pallet, stretch wrap, strapping and corner boards.
- Account for non-stackable freight. If nothing can go on top, tell the carrier; some treat the space above as used.
Pallet weight is easy to forget. A typical wood pallet adds a meaningful amount to the total, and our guide to how much a wood pallet weighs gives typical figures by type. The standard pallet sizes guide lists the footprints most carriers see.
When is a calculated freight class wrong?
A freight class calculator gives the right answer only when your commodity is rated by the density scale. Some NMFC items still carry a fixed class, or a density scale with different brackets, because handling, stowability or liability matters more than weight for that product. In those cases the NMFC item number, not the calculator, decides the class.
Watch for these situations:
- Fixed-class items. Some commodities have one class regardless of density.
- Special-handling freight. Fragile, irregularly shaped or hazardous freight can rate higher than its density suggests. The 2025 NMFC changes also added identifiers that flag freight needing special handling.
- Mixed shipments. Different commodities on one bill of lading may each need their own item and class.
- FAK agreements. If your carrier contract has a freight-all-kinds provision, a range of classes may bill as one class, regardless of what the calculator shows.
NMFTA’s official lookup tool, ClassIT+, shows the item, description and class for a commodity. If you’re not sure whether your product is density-rated, check it there or ask the carrier before you book.
How do you use your freight class once you have it?
The class goes on your quote request and your bill of lading, along with the NMFC item number and the same weight and dimensions you used in the calculation. Consistency between all three is what keeps the invoice matching the quote. Our bill of lading guide shows where each field goes.
Class is one of the biggest inputs to the price, so it’s worth confirming before you compare carriers. The PalletPath freight calculator from ParcelPath uses your dimensions, weight and class to compare LTL quotes from several carriers at once, with no subscription or contract. Our freight calculator guide explains what else goes into an estimate, the LTL freight rates guide shows how class feeds the carrier’s tariff, and the freight shipping quote checklist lists every other detail a quote needs.
If your shipment is small enough for parcel service instead, our shipping calculator guide covers the parcel side. For freight updates and shipping tips, you can also follow ParcelPath on LinkedIn.
Frequently Asked Questions
What is the formula a freight class calculator uses?
A freight class calculator multiplies length, width and height in inches, divides by 1,728 to get cubic feet, then divides the total weight in pounds by that number. The result is density in pounds per cubic foot. That density is matched to the NMFC 13-bracket scale; for example, 27 pounds per cubic foot falls between 22.5 and 30 and rates class 65.
What density is freight class 50 under the new scale?
Freight class 50 applies to freight with a density of 50 pounds per cubic foot or more. It was added to the NMFC density scale by NMFTA Docket 2025-1, effective July 19, 2025, along with class 55 for freight from 35 up to 50 pounds per cubic foot. Before that change, the densest bracket on the standard scale rated class 60.
Does a freight class calculator include the pallet?
Yes. A freight class calculator should use the loaded handling unit, so include the pallet’s height in the height measurement and its weight in the total weight, along with stretch wrap and strapping. Carriers measure and weigh the whole unit at the terminal, and leaving the pallet out produces a density that is too high and a class that is too low.
Is the freight class calculator result always my official class?
No. The calculator result is your official class only when your commodity’s NMFC item is rated by the density scale. Some items carry a fixed class or their own brackets because of handling, stowability or liability. Check the NMFC item in NMFTA’s ClassIT+ tool, or ask your carrier, before putting the class on your bill of lading.
Sources
- NMFTA: Disposition Bulletin 1371, Docket 2025-1 (13-subprovision density scale, effective July 19, 2025)
- NMFTA: NMFTA Implements Historic NMFC Changes, Launches ClassIT+
- National Motor Freight Traffic Association (NMFC)
Part of our LTL class chart guide.
