If you don’t have any hardware on your door, just measure from the edge of the door to the center of the bore hole (the large hole where the door knob assembly is mounted). Standard backsets are either a 2 3/8″ backset, or 2 3/4″ backset. The most common backset is 2 3/8″ but 2 3/4″ is also quite common – usually used on exterior doors. Sometimes it’s easier to measure from the edge of the door to the highest point on the bore hole. If you don’t order the correct backset, your latches will either be too long or too short and you will not be able to mount your door hardware.