To help you work out the Payload for your vehicle see below terminology commonly used on vehicle specification sheets.

Gross Vehicle Mass (GVM)

Gross Vehicle Mass (GVM) in kilograms, is displayed on the Vehicle Compliance Plate (usually found under the bonnet on the firewall) and is also shown on Vehicle Specification Sheets. The GVM is the maximum permissible weight of a fully loaded vehicle including but not limited to the vehicle itself, driver and passengers, all accessories, options, truck body and tow ball mass.

Axle Loads

Maximum Axles Load capacities are specified by the manufacturer of the vehicle. Each axle has a specific capacity which cannot be exceeded.

Gross Combined Mass (GCM)

Gross Combined Mass (GCM) in kilograms, is the maximum permissible weight for your vehicle and trailer combined as specified by the tow vehicles manufacturer.

Kerb Mass (KM)

Kerb Mass (KM) in kilograms is the mass (or weight) of the vehicle with no driver, passengers, payload or truck body.

Aggregate Trailer Mass (ATM)

Aggregate Trailer Mass (ATM) is the total maximum weight a trailer can be when it is not coupled to the tow vehicle. This is the figure quoted when referring to maximum tow ratings for specific vehicles.

Gross Trailer Mass (GTM)

Gross Trailer Mass (GTM) is the maximum weight the trailer can exert on the ground via it’s axle/axles when coupled to the tow vehicle. GTM= ATM-TBM

Tow Ball Mass (TBM)

Tow Ball Mass (TBM) is the amount of weight the trailer exerts on the vehicles tow hitch when coupled to the vehicle. Maximum tow ball mass ratings are shown on the vehicles Towbar assembly. Always refer to vehicles specifications sheet to ensure aftermarket towbars match the ratings stamped on the towbar.

Payload (P)

Payload (P) is the mass (or weight) of cargo/goods/tools the vehicle is permitted to carry.


Every person in a light truck is considered an occupant and is assumed to each weigh 75kgs. The total number of occupants for any truck is shown on the Vehicle Compliance Plate and possibly the Specification Sheet.

Vehicle Compliance Plate

An aluminium plate affixed to the firewall showing the GVM, the recommended number of occupants, the make and model of the vehicle.

Calculating Payload (P)

Payload (P) in kilograms is the GVM minus the following items….(KM) Kerb Mass, weight of the occupants, weight of fuel, oil and water, tow ball downforce, weight of any fitted options (towbar, bull bar, etc) and the weight of the truck body.

Payload (P) = GVM – (Kerb Mass + Fluids + Occupants + Tow ball downforce + options + Truck Body)

It is important to calculate your vehicles loaded GVM, Axle loads and GCM before heading off on an adventure. A GVM upgrade is recommended for most vehicles that plan on adding an extensive range of accessories.


The figures stated in this payload calculator are to be used only as a guide. Accessory masses vary between different body types and vehicle models. For more accurate mass values, please contact your vehicle and accessory manufacturer.