Standard Measurements for Doorknobs
The first step to ordering door hardware is figuring out what you need. It's important to know what your door preparation is so you don't order the wrong hardware for your doors. You will want to check your backset, the bore hole size, cross/edge bore size and the thickness of your door.
To the right or below is a diagram that illustrates a bore hole and a cross/edge bore. The bore hole is the large hole where the door knob is inserted and mounted. The cross/edge bore is the small hole on the edge of the door. The door latch is inserted into the cross/edge bore first. The latch goes through into the large bore hole and then the door knob is mounted The backset is the distance from the edge of the door to the center of the large bore hole. The standard backset is 2 3/8" or 2 3/4". Most doors are 2 3/8" backset (residential), but some have a 2 3/4" backset (commercial).
While many door knob manufacturers ship their hardware with an adjustable backset, some do not. You may be asked for this information when ordering.
Door thickness can vary. Most interior doors are 1 3/8" thick. Exterior doors are often 1 3/4" thick. Most door hardware manufacturers make their products to fit these standard thicknesses. If you have a thicker door, your hardware will need to be custom ordered (call 256-654-5757).
2 3/8" - 2 3/4"
Standard Bore Hole:
2 1/8" Dia.
Standard Cross Bore: