Home lock calculator
Door Thickness Compatibility Checker
See whether your door falls within a common residential thickness range.
Result
In standard range (1 = yes)
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Outside range by (in)
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Formula
Calculation logicDoors outside the common range may need special hardware. Follow the lock manufacturer instructions.
How to Measure Door-Lock Prep
Take these four readings first
- Door thickness. Calipers on the slab edge, three spots, keep the largest. Stock locksets cover 1-3/8 to 1-3/4 in.
- Face bore. Tape across the widest point of the large hole. US standard is 2-1/8 in.
- Edge bore. The small latch hole is 1 in on standard prep.
- Backset. Door edge to bore-hole center: 2-3/8 or 2-3/4 in.
Photograph before you shop
One photo per reading, plus a wide shot of hinges and strike. A locksmith can quote from photos; a purchase cannot be returned once a door is drilled.
Verify before you buy
- Measure top, middle, bottom; keep the largest
- Exclude trim and weatherstrip
- Confirm kit range for thick doors