If you are posting an item that takes up a lot of space but isn't very heavy, a postage company might charge you for the item's dimensional weight instead of its actual weight. Light packages that take up a lot of room in a postage trucks or airplanes actually cost the company money to post if they are charged based only on their actual weight.

Postage companies will not post items that exceed a certain dimensional weight.

Find out how to calculate cubic weight equivalent for Australia Post parcels.