Measuring the backset on an Adams Rite mortice lock is pretty straightforward, but it’s important to get it right—especially for compatibility with door stiles, handles, and cylinders. When measuring the backset it is Important to note that it has to be measured with the faceplate attached to the forend, measuring with the forend only will give you a misreading.
What Is the Backset?
The backset is the distance from the faceplate of the lock (the front edge that’s visible on the door stile) to the center of the cylinder hole or spindle hole.
How to Measure It:
Identify the Faceplate:
This is the narrow, vertical metal strip that sits flush with the edge of the door.
Find the Cylinder or Spindle Center:
Look for the central hole where the key cylinder or handle spindle goes through the lock body.
Measure the Distance:
Use a ruler or caliper to measure from the edge of the faceplate to the center of the cylinder hole.
Be as precise as possible—common sizes are 22.2mm, 24.6mm, 28.6mm and 38.1mm, depending on the lock model and application.
