Volumetric weight, also known as dimensional weight is used by postal companies and other freight industries and courier services around the world to invoice for the actual space that a parcel, package or pallet takes up in a vehicle or storage area. A vehicle can quickly become full of bulky, lightweight articles long before it reaches its capacity in weight which makes for inefficient use of space.

The basic procedure for calculating volumetric weight is:
  • Measure the box's length, width and height in centimetres. Measuring twice is always a good idea to reduce the incidence of error.
  • Write down each of the dimensions on the piece of paper. Remember that you need to use centimetres rather than inches or other units.
  • Multiply the length by the width. You will get the surface area of one side of the box in square centimetres.
  • Multiply the resulting area from Step 3 by the height of the box. This number represents the actual volume of the box in cubic centimetres.
  • Divide the volume by 6,000. The result is the standard volumetric weight of the box in kilograms

The result of this calculation is that if your consignment's density is one-sixth that of water or more, then its volumetric weight is less than the normal weight in kilograms, whereas if its density is less than one-sixth that of water, then its volumetric weight is more than its weight in kilograms. Transport and postal companies will charge based on the greater of these two calculations.

Increasingly, carriers, postal companies and warehouses are using dimensional calculators to measure the volumetric weight of their parcels and pallets.

Companies with large shipping departments use these systems to measure all outgoing items to ensure that they don't receive back charges from their carrier who invoices using the dimensional weight rate system.