Finding the right place for a desk needs more floor space than just the size of the item itself, as you will need about 50-76 cm behind the chair. Reserving this space means that you can push the chair back to get up, or turn around to reach a credenza or bookshelf behind you. Together with the chair, this means keeping an area 100 cm deep free in front of a desk. For example, 40 cm deep desks would require a 140 cm deep floor space in total. The extra area behind the chair doesn't need to be dead space, as it can double as the space you need to get to a dresser, filing cabinet, or a bookshelf.