Door Lock Backset Measurement

Pack your locks with a 2 3 8 inch or 2 3 4 inch latch depending on which backset you specify.

Door lock backset measurement.

The most common backset is 2 3 8 but 2 3 4 is also quite common usually used on exterior doors. The backset is measured by placing a tape measure or ruler from the center of the keyhole to the forend of the mortice lock. Mortised latches come in a radius corner rounded on the edges or a squared corner configuration. These equate to case sizes of 2 1 2 or 3 in imperial measurements.

These smaller backset sizes are generally european and some are still in use today. 5 backsets are only available for some schlage locks and some kwikset locks. Please see the demonstration below. Sometimes it s easier to measure from the edge of the door to the highest point on the bore hole.

Backsetthe distance from the edge of the door to the center of the lock bore. Dead bolt latches top 2 3 4 bottom 2 3 8 note. Falcon used to make a 5 backset that would work with emtek hardware but i believe it is no longer available. To do this measure the backset distance of your old lock.

There is a range of backset long body locks at 20mm 25mm 30mm 35mm 40mm 50mm and 70mm. In the uk and much of europe these dimensions can vary from 25 to 60 mm and many medallion knobs are placed in the center of the door creating a very large backset. Two standard backsets are 2 3 8 and 2 3 4. Some older residences will have variations to installed locks.

The backset measurement is the distance from the centre of the keyhole to the leading edge of the lock. In the united states there are two common backsets for residential door locks. Other backsets include 2 used by national and lori lock and 5 used by weiser weslock kwikset and others. Standard backsets are either a 2 3 8 backset or 2 3 4 backset.

2 3 8 inches and 2 3 4 inches. The backset is the distance from the edge of the door to the center of the 2 1 8 inch bore hole. If you dont 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. Almost all domestic mortice locks and tubular latches are supplied with either a 44mm or 57mm backset length.

Most commercial doors have a backset of 2 3 4 inches 69 8 mm while residential doors measure 2 3 8 inches 60 3 mm. Check the other dimensions too most of our pages show plate and lock case dimensions.