Typically, a piece of equipment being installed has a front panel height inch () less than the allotted number of Us. Thus, a 1U rackmount computer is not tall but is tall. If "n" is number of rack units, the ideal formula for panel height is h = (1.75"n" − 0.031) for calculating in inches, and h = (44.45"n" − 0.794) for calculating in millimetres. This gap allows a bit of room above and below an installed piece of equipment so it may be removed without binding on the adjacent equipment.