The US Changed Its Freight Class Rules in July. Most Calculators Didn't Notice.

In July 2025, the NMFTA rewrote the density scale that decides freight class for most LTL shipments in the US (Docket 2025-1, effective July 19, 2025). I built CheckFreightClass because a surprising share of the calculators online still answer from the old table — including answering "class 500" from density, which the current scale cannot produce at all.

What actually changed

Most commodity items that used to carry their own printed class now classify by density alone, and the density scale grew from 11 to 13 classes. The scale in force today:

That single table is the whole engine. On the site it lives in exactly one place — one data file that the calculator, the printable freight class chart and the test page all read from. When the table is the product, duplicating it across pages is how you end up disagreeing with yourself.

The calculation, and the boundary that matters

Density is weight divided by volume: measure each piece in inches (pallet and overhang included), divide cubic inches by 1,728 for cubic feet, then divide pounds by cubic feet.

• 48 × 40 × 48 in at 500 lb → 53.33 ft³ → 9.38 lb/ft³ → class 100
• 40 × 48 × 48 in at 20 lb → the same 53.33 ft³ → 0.38 lb/ft³ → class 400

The boundaries are where calculators quietly differ, so I published the test cases instead of asking anyone to trust the tool: the public test page lists inputs and the class the current scale should give, including the exact-boundary case at 10.00 lb/ft³, which belongs to 92.5, not 100. If your calculator disagrees, the page shows its working.

Three mistakes that cost shippers money

1. Pooling pieces into one density. Two pieces with different densities classed as one blended number can push the whole shipment into a worse class. Class each piece on its own.
2. Using a pre-2025 table. Any chart showing 18 classes, or a density band ending at class 500, predates the current scale.
3. Forgetting the pallet. Height and weight are measured on the complete loaded piece — pallet, wrap and all. A few inches of pallet height moves the density, and the density moves the class.

Why a test page

The pattern I keep coming back to on these small tool sites: don't just ship the calculator, ship the evidence that it's right. A page of worked cases with expected outputs costs an afternoon, and it's the page that earns the link when someone in a forum thread asks "is this class right?" — because it answers the question instead of asking for trust.

If you ship LTL and your quotes still come back with classes off the old scale, I'd genuinely like to hear what your carrier's audit adjusted and why.