Abstract: A graphical user interface is provided for providing a three dimensional representation of a cargo storage space and a three dimensional representation of a cargo item to be placed within that storage space. The interface allows the representation of the cargo item to be moved to different positions in the storage space within the constraints of the real dimensions of the storage space and of the cargo item. Therefore a user may use the interface to plan the storage of cargo within a certain space such as the hull of a ship or aircraft. In this way, efficiency of cargo storage can be improved. Methods for determining the shape of a number of cargo items in a selected space, and for determining whether or not a cargo item of a given shape will fit within a predetermined space are also provided.