Common Door Prep Sizes in U.S. Homes & How to Measure Correctly
Before buying door hardware, it’s important to know whether it fits your door.
Here are the standard U.S. measurements and how to measure them correctly.
1. Door Thickness (Most Common: 1-3/8” to 1-3/4”)
✔ Interior doors: 1-3/8”
✔ Exterior doors: 1-3/4”
To measure, use a ruler or caliper to check the thickness at the door’s edge.
2. Bore Hole Diameter (Standard: 2-1/8”)
The bore hole is the round hole where your knob or lever is installed.
Most U.S. homes use 2-1/8” diameter.
3. Backset Measurement (2-3/8” or 2-3/4”)
This is the distance from the door edge to the center of the bore hole.
✔ Common for interior doors: 2-3/8”
✔ Common for exterior doors: 2-3/4”
4. Latch Faceplate Sizes
Two main types:
✔ Square corner
✔ Round corner
Match your existing door prep for easiest installation.
5. Measuring Tips for Older Homes
Vintage doors may not follow modern standards—use backplates or adjustable latches when needed.
