A face-frame cabinet is a cabinet which has a front panel into which an opening has been cut. An overlay door is a door which, when closed, lays “on top” of the cabinet opening (no part of the door goes into the opening since the door is larger than the opening). The overlay dimension is simply how much bigger the door is than the opening of the cabinet (as measured on the hinged side of the door).
Here is how to measure your door overlay on a face frame cabinet, (the measuring process is basically the same for a frameless cabinet):
Overlay Door – note the door sits in front of face frame and is larger than cabinet opening.
Line up the edge of your door with the edge of a piece of tape and apply the tape to the face frame of the cabinet (must be on the hinged side of the door).
Now, open the cabinet door and measure from the edge of the tape (inside edge) to the edge of the opening of the cabinet. In this case the overlay is 1-1/4″. The example shown above is of a European hinge but the process is the same for any kind of overlay hinge.
Another way to look at door overlay: If your door is 30″ wide and the opening is 28″ wide then then you could calculate your overlay as 30 minus 28 divided by 2 equals 1″. Divided by two because the overlay is measured on one edge, the hinged edge of the door. This method is not recommended as a way to measure your overlay because it is not as accurate as the tape method.