From the operator's point of view one of the most important dimensions on the forklift truck is the load centre. This is defined as the distance from the front face of the forks to the centre of gravity of the load and the internationally recognised standard for this dimension is 500 mm.
Other dimensions are used in certain circumstances. For example a huge container handler on the dockside might have a load centre of 1000 mm or more. Similarly a narrow aisle, man up, turret truck may have a small load centre of only 400 mm. Before the UK went metric the common load centre was 24 inches and this is still found occasionally on some older trucks