Article

Face Bore and Edge Bore Sizes

Updated October 11, 2026

Two holes, two jobs

Every bored residential door has two holes. The face bore is the big hole through the door faces (standard 2-1/8 in). The edge bore is the small hole in the door edge where the latch or bolt lives (standard 1 in). Replacement hardware must match both.

Face bore: what the numbers mean

• 2-1/8 in — modern standard. Deadbolts, knobs, levers, smart locks all fit.
• 1-1/2 in — older doors and some knobs. A deadbolt will not cover it; use a bore adapter ring or replace the slab.
• Oversize or damaged — wrap-around reinforcement plates rescue the door without replacing it.

Edge bore and latch

The edge bore carries the latch case. Match it to the latch backset with the latch checker, and confirm the faceplate shape (drive-in, round-corner, square-corner) against the faceplate guide.

Check both at once

Run the bore compatibility checker with both diameters. If either deviates more than 1/16 in from standard, read the full prep walkthrough before buying.