What is axle weight?

Axle weight is the portion of a vehicle's total weight carried by a single axle or axle group — the number weigh stations and the Bridge Formula regulate.

Axle weight is the share of a loaded vehicle's total weight that presses down through one axle (or one closely-spaced group of axles) onto the road. It is what a weigh-station scale measures axle by axle, and it is what most weight laws actually regulate — because road and bridge damage depends on load per axle, not just the total.

How it's limited

US federal Interstate limits cap a single axle at 20,000 lb and a tandem group at 34,000 lb, while the Bridge Formula limits each group further by how far its axles are spread. A load can be under the 80,000 lb gross limit and still be illegal because one axle group is overloaded.

What changes it

Axle weights shift with where cargo sits in the trailer: moving the center of gravity forward puts more weight on the drive axles and less on the trailer axles. Sliding the tandem or the fifth wheel redistributes it. That is exactly what a load planner solves for.

Check a real load in secondsLoadLegit turns axle weights into a pass/fail compliance verdict — federal Bridge Formula plus verified state and Canadian rules — and issues a shareable certificate. Try it free →

What is gross vehicle weight (GVW)?Gross vehicle weight (GVW) is the total actual weight of a fully loaded vehicle — tractor, trailer, fuel, driver and cargo. The federal Interstate limit is 80,000 lb.What is a tandem axle?A tandem axle is two axles spaced close together (typically 40–96 inches) that share a load as one group. The US federal tandem limit is 34,000 lb.What is the Federal Bridge Formula?The Federal Bridge Formula (W = 500(LN/(N-1)+12N+36)) sets the maximum legal weight on any group of axles based on how far apart they are spread.Axle weight limit checker (federal)Check steer, drive, and trailer axle weights plus gross weight against the US federal limits: 20,000 lb single, 34,000 lb tandem, 80,000 lb gross.