Close the cabinet door. If working with new cabinetry, place the blank door over the cabinet opening with the sides overlapping evenly. Ask a friend to hold the door in place.
Make a mark on the cabinet at the edge of the door on the hinge side with a pencil. The mark only needs to be large enough for you to see.
Open the cabinet door or remove the new door blank from the cabinet. Measure from the mark to the edge of the opening with a tape measure. This is the hinge overlay measurement.