The two important variables when installing a lockset are the height of the knob above the finish floor and the backset—the distance from the center of the knob to the near edge of the door. Most knobs are positioned a comfortable 36 or 38 inches above the floor; check the height of other knobs in the house and keep it consistent.
Backset typically measures 2 3/8 inches for interior doors and 2 3/4 inches for exterior doors. The point at which the knob height and the backset measurements intersect represents the center of the face bore, the circular hole that houses the lockset. A second hole, the edge bore, contains the latch assembly Most locksets come with a cardboard template to help align the two bores. Check the template for the lock's bore diameters and choose drill bits accordingly.