How to Calculate Freight Density and Class (2026)

Why density decides what your LTL shipment costs

A carrier’s trailer runs out of space long before it runs out of weight, and that single fact explains most of LTL pricing. If your 600-pound pallet occupies the same linear feet as someone else’s 3,000-pound pallet, the carrier earns a fraction of the revenue for the same slot — so the pricing system charges you for space, not just the scale reading. Density, in pounds per cubic foot, measures that space cost.

Get density right and your quote holds. Get it wrong and a rebill arrives weeks later, usually with an inspection fee attached.

The density formula, step by step

Three steps.

Step 1: Measure length, width and height in inches

Measure the shipment as it will be tendered, not as it sits in your ERP:

• Include the pallet in the height — a standard pallet adds roughly five to six inches.
• Include overhang. Carriers measure the outermost point, so cartons hanging two inches past the pallet add two inches to your width.
• Include shrink wrap, banding, corner boards and any protruding hardware.
• Round up to the nearest inch. Carriers do.

Step 2: Convert to cubic feet

Multiply length by width by height to get cubic inches, then divide by 1,728 (that is 12 × 12 × 12, the number of cubic inches in a cubic foot).

Step 3: Divide weight by cubic feet

Divide the total weight of the handling unit — product, packaging and pallet — by the cubic feet. That is your density in pounds per cubic foot (lbs/ft³). For multi-pallet shipments, total the weight and total the cubic feet across all units, then divide.

A worked example

Cartons stacked on a 48″ × 40″ pallet, 45 inches tall including the pallet, overhanging the pallet by two inches on one side. Scale weight: 630 pounds.

• Dimensions as tendered: 48″ × 42″ × 45″ (the 40″ width becomes 42″ because of the overhang)
• Cubic inches: 48 × 42 × 45 = 90,720
• Cubic feet: 90,720 ÷ 1,728 = 52.5 ft³
• Density: 630 ÷ 52.5 = 12 lbs/ft³

Ignore the overhang and quote 48″ × 40″ × 45″ instead, and you get 86,400 cubic inches, 50 cubic feet, and a density of 630 ÷ 50 = 12.6 lbs/ft³. Two inches of overhang moved the number by five percent — on a threshold-sensitive commodity, enough to change the class and trigger a rebill.

For contrast, a tightly packed skid measuring 48″ × 40″ × 36″ (69,120 ÷ 1,728 = 40 ft³) weighing 1,200 pounds comes out at 30 lbs/ft³ — dense freight that prices far more favorably per hundredweight.

How density maps to freight class

The direction is simple: higher density means a lower class number, and a lower class number means a lower rate per hundredweight. A pallet of bolts is dense, cheap to move per pound, and lands at a low class. A pallet of foam insulation is light and bulky and lands at a high class.

What you should not do is memorize a density-to-class chart from the internet and treat it as gospel. The NMFTA has been moving the National Motor Freight Classification toward a more consistently density-based structure, and treatment for individual commodities continues to change. Some items still carry a fixed class regardless of density; others are classed on a density scale. Always verify the current NMFC treatment for your specific commodity with the current classification or your carrier or 3PL before building a rate assumption on it. Our deeper look at freight class and NMFC codes for Miami LTL shippers covers how to run that check.

The four NMFC characteristics

Density is the loudest of four factors, not the only one:

• Density — pounds per cubic foot, as calculated above.
• Stowability — how well the freight loads with other freight. Excessive length, awkward shapes, hazmat that cannot be co-loaded, and non-stackable items all hurt stowability.
• Handling — whether it moves with a standard forklift and standard care. Fragile, unpalletized or oddly balanced freight does not.
• Liability — the carrier’s exposure. High-value, theft-attractive, perishable or hazardous goods carry more risk per pound.

What triggers a reweigh or reclass inspection

Carriers run automated dimensioners at their terminals. Freight is photographed and measured in seconds, and any variance from the bill of lading is flagged. Common triggers:

• Dimensions on the BOL that do not include the pallet or overhang
• Weight rounded down, estimated, or copied from a previous shipment
• A generic product description that does not match any NMFC item
• Missing or wrong NMFC number
• Piece count on the BOL that does not match the handling units on the dock

To avoid it: weigh on a certified scale, tape-measure the built pallet, list the NMFC item number and class explicitly, use the classification’s own commodity language, and state the correct handling-unit count. If your product ships in several configurations, keep an internal table of dimensions and weights so whoever writes the BOL is not guessing.

Dimensional and cube rules to watch

Two rules can override your calculated density. Cubic capacity rules rerate a light shipment at a minimum density assumption once it exceeds a set cubic-foot volume at low density. Linear foot rules apply when a shipment consumes more than a set number of linear feet of trailer floor, regardless of weight. Both live in the carrier’s rules tariff and vary by carrier — read them before tendering an unusually light or long load.

Practical packing tips that improve density

• Build down, not up. Cutting stack height from 60 to 48 inches on the same footprint removes 20 percent of your cube and raises density accordingly.
• Eliminate overhang. Choose a carton size that tiles the pallet footprint cleanly.
• Consolidate partial pallets. Two half-full skids are two handling units and roughly twice the cube of one full skid.
• Wrap tight. A square, well-wrapped pallet measures smaller and survives handling — see our guide to palletizing LTL freight to avoid damage claims.

For a second set of eyes on how your freight is classed, our LTL team in Miami reviews commodity descriptions and dimensions before shipments go out.

Frequently asked questions

How do I calculate freight density?

Multiply the shipment’s length, width and height in inches — including the pallet, overhang and packaging — to get cubic inches. Divide that number by 1,728 to get cubic feet. Then divide the total weight in pounds by the cubic feet. The result is your density in pounds per cubic foot.

Does higher density mean a lower freight class?

Generally yes. Denser freight uses less trailer space per pound, so it typically falls into a lower class number and a lower rate per hundredweight. Density is not the only factor — stowability, handling and liability also matter, and some commodities carry a fixed class. Verify the current NMFC treatment before assuming a class.

What causes a carrier to reclassify my shipment?

The most common causes are dimensions that omit the pallet or overhang, estimated rather than scaled weights, vague commodity descriptions, a missing or incorrect NMFC number, and a piece count that does not match the dock. Automated dimensioners flag the variance and the carrier rebills, often with an inspection fee.

Not sure how your freight should be classed? Send the dimensions and weight to rates@gofreighthub.io or call Go Freight at (786) 449-4020 and we will check it before it costs you a rebill.