HOW TO MEASURE A LOCKCASE/GEARBOX

A - Handle/spindle centre
The distance from the centre of the keyhole to the centre of the handle/spindle. In this example, there are two possible spindle points.

B - Lockcase length
The distance from the top to the bottom of the lockcase which sits inside the door itself.

C - Backset
The distance from the middle of the spindles to the front face of the lock.

D - Faceplate length
The distance from the top to the bottom of the faceplate which sits flush on the door.

E - Lockcase depth
The distance from the faceplate to the back of the lockcase.

F - Faceplate width
The horizontal width of the faceplate that sits flush to the door.

G - Lockcase width
The horizontal width of the lockcase that is inserted into the void in the door.