Curb weight refers to the total weight of a vehicle, inclusive of standard equipment and necessary operating fluids such as motor oil, transmission oil, and brake fluid, but without passengers or cargo. It is essentially the weight of a ready-to-drive vehicle without any load. On the other hand, gross weight denotes the total weight of a vehicle when it is fully loaded with passengers, cargo, and any additional equipment. Gross weight is the sum of the curb weight and the additional load.

Curb weight is an important element in vehicle specifications. It takes into account everything necessary to operate the vehicle but nothing that would be considered a variable payload. This base weight plays a key role in how a vehicle performs and how much fuel it uses. Gross weight, a variable measure, dictates the payload capacity of the vehicle.

Specification sheets often list curb weight for a given model as a range because of differing optional equipment such as all-wheel-drive systems or engine selections. The United States Environmental Protection Agency regulations define curb weight as the actual or the manufacturers estimated weight of the vehicle in operational status with all standard equipment, and weight of fuel at nominal tank capacity, and the weight of optional equipment computed in accordance with §86.1832–01.