SAE J1100 - Motor Vehicle Dimensions was first published in September 1973. One of the many significant aspects of this recommended practice is that it provides procedures for estimating cargo/luggage volume in various types of vehicles. Passenger vehicles typically carry cargo in one of two areas: those that are separate from the passenger compartment and those that are open to the passenger compartment. A closed compartment is: An area intended to carry or stow luggage or cargo for personal or commercial purposes that is distinct or enclosed from the area used to transport people. The volume of this area is quantified by a physical stack of simulated luggage pieces, and include the following body types: coupes, sedans, and convertibles.An open compartment is: An area intended to carry or transport luggage or cargo for personal or commercial purposes that is open to the passenger compartment. These areas have the potential to carry people or cargo. The volume of this area is estimated by multiplying the compartments representative length, width and height, and include station wagons, minivans, multi-purpose vehicles, and hatchbacks.Due to the flexibility of carrying either people or cargo, open compartment volumes are more challenging to quantify. Therefore, the purpose of this paper is to provide guidance and explanation of how SAE J1100 metrics are applied to open compartment vehicles (closed compartment metrics are not discussed). The paper also expands upon the rationale in the SAE document and demonstrates the principles by example. This will result in a more accurate and uniform reporting of cargo volumes determined by these methods.