Home lock calculator
Door Lock Size & Compatibility Checker
Check common residential door-lock dimensions before buying a replacement.
Result
Fit score (3 = full match)
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Backset match (1 = yes)
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Bore match (1 = yes)
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Thickness match (1 = yes)
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Formula
Calculation logicThis is a screening tool. Confirm the exact lock model and installation instructions before purchase.
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
- Re-measure backset edge-to-center, not to trim
- Confirm bore with the maker template
- Check thick-door kit range before checkout