GVWR, GCWR, GAWR and Curb Weight Explained

US & Canada

The acronyms, quoted from the regulations that define them, and an honest note about the one that no regulation defines.

The four that matter

Towing weight ratings, what each one covers and where it comes from
Term What it is Standing
GVWR
Gross vehicle weight rating 		The most the vehicle may weigh, loaded. Set by the manufacturer, printed on the door sticker. Defined in regulation
49 CFR 571.3, Definitions
GAWR
Gross axle weight rating 		The most one axle may carry, measured at the tires. There is a front and a rear figure, and they are separate from GVWR. Defined in regulation
49 CFR 571.3, Definitions
UVW
Unloaded vehicle weight 		The vehicle with all fluids full but no people, cargo or removable accessories. What most people mean by curb weight. Defined in regulation
49 CFR 571.3, Definitions
GCWR
Gross combination weight rating 		The most the vehicle and trailer may weigh together. Comes from the manufacturer, usually via the SAE tow-rating standard. Set by the manufacturer; defined for CDL purposes in 49 CFR 383.5
SAE J2807, Performance Requirements for Determining Tow-Vehicle Gross Combination Weight Rating and Trailer Weight Rating

The thing nobody tells you about GCWR

GVWR, GAWR and unloaded vehicle weight are all defined in United States federal regulation, at 49 CFR 571.3, Definitions. You can read the exact wording and hold a manufacturer to it.

GCWR is not. It does not appear in that definitions section. It is a figure the manufacturer assigns, in practice by testing against SAE J2807, Performance Requirements for Determining Tow-Vehicle Gross Combination Weight Rating and Trailer Weight Rating, which is a paywalled industry standard rather than law. That does not make it optional, since exceeding it voids the basis on which the vehicle was validated. But it does mean GCWR can differ between two sources for the same truck, and the manufacturer's own current towing guide is the one to trust.

In the regulator's words

Gross vehicle weight rating
"Gross vehicle weight rating or GVWR means the value specified by the manufacturer as the loaded weight of a single vehicle." 49 CFR 571.3, Definitions
Gross axle weight rating
"Gross axle weight rating or GAWR means the value specified by the vehicle manufacturer as the load-carrying capacity of a single axle system, as measured at the tire-ground interfaces." 49 CFR 571.3, Definitions
Unloaded vehicle weight
"Unloaded vehicle weight means the weight of a vehicle with maximum capacity of all fluids necessary for operation of the vehicle, but without cargo, occupants, or accessories that are ordinarily removed from the vehicle when they are not in use." 49 CFR 571.3, Definitions
What a GVWR must cover, at minimum
"which shall not be less than the sum of the unloaded vehicle weight, rated cargo load, and 150 pounds times the number of the vehicle's designated seating positions." 49 CFR 567.4(g)(3)

That last one is where this site's 150 lb per person comes from. It is not an estimate of an average adult, it is the allowance the rating itself is built on.

Canada: the same ratings, two languages, one extra rule

Canadian vehicles and trailers carry a compliance label with the same ratings, given under both the English and French terms or under both abbreviations. So a trailer plate reading PNBV is giving you the gross vehicle weight rating, in kilograms. Motor Vehicle Safety Regulations (C.R.C., c. 1038), s. 6(1)(e)(i) requires "the gross vehicle weight rating, expressed in kilograms, clearly identified by the words 'Gross Vehicle Weight Rating' and 'Poids nominal brut du véhicule' or the abbreviations 'GVWR' and 'PNBV'", and it names trailers in the same breath as cars and trucks.

The Canadian minimum, at Motor Vehicle Safety Regulations (C.R.C., c. 1038), s. 5.2, works the same way as the American one but in metric: unloaded mass, plus cargo capacity, plus an occupant allowance of 68 kg per seat, 54 kg for school buses. 68 kg is 150 lb, so the two countries agree on the person. Canada adds one thing the American rule does not mention: on a vehicle with living quarters, the mass of the water and propane tanks counts too.

Consolidated regulations are amended. The wording above was checked against the linked sources on 2026-10-23, and the two Canadian sections again on 2026-10-24. For anything consequential, read the section as currently in force rather than this page.

Sources

Common questions

What does GVWR mean?
49 CFR 571.3, Definitions defines it: "Gross vehicle weight rating or GVWR means the value specified by the manufacturer as the loaded weight of a single vehicle." In plain terms, the most your vehicle is allowed to weigh with everything and everybody in it. It is not the weight of the vehicle, and it is not how much it can carry.
What is the difference between GVWR and GCWR?
GVWR covers one vehicle. GCWR covers the vehicle and the trailer added together. A rig can be inside GVWR and over GCWR, or the reverse, which is why both have to be checked. There is a further catch: GVWR is defined in federal regulation, and GCWR is not. It is a manufacturer figure, so where you read it matters.
What does GVWR mean on a trailer?
The same thing: the most that trailer may weigh, loaded. Trailer GVWR minus its empty weight is its cargo capacity, which is the number that tells you what you can actually put in it.
Why does my Canadian trailer plate say PNBV?
Because the compliance label has to give the rating under both the English and French terms, or under both abbreviations. PNBV is "Poids nominal brut du véhicule", the French for gross vehicle weight rating. Motor Vehicle Safety Regulations (C.R.C., c. 1038), s. 6(1)(e)(i) is the labelling requirement, and it names trailers explicitly. The number beside it is the same number, in kilograms.
Is GVWR the sum of the axle ratings?
No, and assuming it is will get you into trouble. GVWR is usually lower than the two GAWRs added together. You can be comfortably under GVWR and still over the rear GAWR, which is exactly what a heavy trailer tongue does.
What is the difference between dry weight and curb weight?
Dry weight is a marketing figure, typically the vehicle or trailer as it left the line with no fluids and no options. Curb weight, defined as unloaded vehicle weight, includes "Unloaded vehicle weight means the weight of a vehicle with maximum capacity of all fluids necessary for operation of the vehicle, but without cargo, occupants, or accessories that are ordinarily removed from the vehicle when they are not in use." Dry weight is always the smaller and more flattering number. Never plan a tow with it.
What GVWR requires a CDL?
In the United States, the thresholds are set by the Federal Motor Carrier Safety Administration and turn on combined weight as well as GVWR, with a widely cited line at 26,001 lb. Canada does not use CDLs at all; licence classes are provincial. Both are covered on their own page rather than summarised loosely here.
Where do I find these numbers?
GVWR and both GAWRs are on the certification label on the driver's door or pillar, and on a Canadian vehicle they appear in English and French. Curb weight is in the manual, but a weigh scale is better. GCWR and the tow rating are in the towing section of the manual or the manufacturer's towing guide. None of them is in the VIN.