Where the class breakpoints come from
The dataset behind both calculators is the density-to-class table published as part of the National Motor Freight Classification (NMFC), the industry standard maintained by the National Motor Freight Traffic Association (NMFTA). The 18 classes from 50 to 500 and the density ranges attached to each one come directly from that published standard rather than an internal estimate.
How the calculators are checked
Before any change to the density formula or the class breakpoints ships, it gets run against a set of known shipments with a published class outcome. A 500-pound pallet at 48 by 40 by 48 inches, for example, should return Class 70, and the calculator's output is checked against that before anything goes live.
Update cadence
The NMFC standard is revised periodically through the docket process the NMFTA runs. Most changes affect specific commodity item numbers rather than the general density breakpoints, but when a breakpoint or class definition does shift, the reference table and CSV download on this site get updated to match. We check for pending NMFC changes a few times a year rather than on a fixed monthly schedule, since the docket calendar itself isn't monthly.
Corrections
If a class, density range or worked example on this site looks wrong, tell us through the contact page and include which page and what you think it should say. We check it against the current NMFC docket and correct it, usually within a few days.
Who is responsible for this
ClassYourFreight is run by Chris Terry, who built both calculators and owns any change to their formulas or the underlying data. Guide content on this site is written by Marcus Vance; his author page has more on his background.