Vehicle weights explained

Vehicle categories on driving licences can depend on the weight of the vehicle - the different terms you might see are explained below.

This guide is also available in Welsh (Cymraeg).

Unladen weight

The unladen weight of any vehicle is the weight of the vehicle when it’s not carrying any passengers, goods or other items.

It includes the body and all parts normally used with the vehicle or trailer when it’s used on a road.

It does not include the weight of:

  • fuel
  • batteries in an electric vehicle - unless it’s a mobility scooter or powered wheelchair

Mass in running order

This is the total weight of a vehicle when it’s empty and ready to be used on the road without carrying any passengers, goods or other items.

Cars, buses and lorries

Mass in running order for cars, buses and lorries includes the driver, the body and all parts normally used with the vehicle along with essential fluids like oil and a full tank of fuel.

Motorbikes, mopeds and quad bikes

Mass in running order for motorbikes, mopeds and quad bikes does not include the weight of:

  • the driver that weighs up to 75kg
  • the machines or equipment installed on the load platform area
  • batteries for electric vehicles 
  • storage tanks for gaseous fuel 
  • storage tanks for compressed air for vehicles that run on pre-compressed air

Maximum authorised mass

Maximum authorised mass (MAM) means the weight of a vehicle or trailer including the maximum load that can be carried safely when it’s being used on the road.

This is also known as gross vehicle weight (GVW) or permissible maximum weight.

It will be listed in the owner’s manual and is normally shown on a plate or sticker fitted to the vehicle.

The plate or sticker may also show a gross train weight (GTW), also sometimes called gross combination weight (GCW). This is the total weight of the tractor unit plus trailer plus load.

Down-plating

If a vehicle is unlikely to be used at its potential maximum weight, it may be ‘down-plated’. This means that a lower weight is shown on the plate or sticker attached to the vehicle.

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