Learn how to measure your door's backset before replacing an existing lock or latch to ensure you get the right fit for your new hardware.
The backset is the distance from the edge of the door to the center of the 2-1/8-inch bore hole. In the United States, there are two common backsets for residential door locks: 2 3/8 inches and 2 3/4 inches. Pack your locks with a 2-3/8-inch or 2-3/4-inch latch, depending on which backset you specify. Dummy sets have no latch and are surface-mounted so you can install a dummy set wherever you choose on the door.
The door prep is a set of drilled holes in the door, where the latch will fit in. If you’re replacing existing locks, then your door preps will most likely be correct for most locks. Just determine the backset, and you're ready to buy or order. If you're installing locks in new doors that don’t have a door prep, you can follow the instructions below.
Passage, privacy, key-in-knob, or lever, and deadbolt locks
Fit into the door prep shown above. Bore a 2-1/8-inch hole through the door. The center of this hole should be located 2 3/8 inches or 2 3/4 inches back from the edge of the door. (This is the backset dimension.) Bore a 1-inch hole in the edge of the door located on the centerline of the 2-1/8-inch hole. The latch will fit into the 1-inch hole. Chisel out a 1-inch-by-2-1/4-inch rectangle on the edge of the door, 1/8 of an inch deep. The latch faceplate will sit in this recession.
Require no door prep. Dummy handles are surface-mounted and may be located anywhere on the door you choose, but they’re usually located to match the appearance of nearby operating locks.
Standard Exterior Doors
The standard size for an exterior door is 80 inches (6 feet, 8 inches) by 36 inches (3 feet). Stock exterior doors are also commonly available in 30-inch and 32-inch widths. The standard door thickness is 1 ¾ inches. Some door manufacturers carry stock doors in 7-foot and 8-foot heights and door widths from 24 inches to 42 inches.
Patio doors are constructed of glass with a frame. The standard size is 6 feet, 8 inches tall and 6 feet wide. However, patio doors are routinely available in 6-foot, 11-inch and 8-foot heights.
Standard Interior Doors