Calculator
Deadbolt Backset Measurement Checker
Identify a common 2-3/8 inch or 2-3/4 inch deadbolt backset.
Open calculatorUS residential lock tools
Door lock calculators for US homes.
Free calculators for American homeowners checking door-lock fit, smart-lock compatibility, rekeying, lock changes, and everyday access planning.
Method
Inputs in. Math shown.
- Measure first.Thickness, bore, backset, counts, and prices. No hidden estimates.
- Every output labeled.Fit scores, deviations, budgets, intervals. Each with its formula.
- Field-check before relying.Templates, photos, quotes, and local code.
Calculators
Start with the question in front of you.
Calculator
Door Bore Hole Compatibility Checker
Compare your face bore and edge bore measurements with common lock preparation.
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Door Handing and Swing Checker
Record hinge side and swing direction before buying handing-specific hardware.
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Door Latch Backset Checker
Check a replacement latch backset against common residential sizes.
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Door Lock Size & Compatibility Checker
Check common residential door-lock dimensions before buying a replacement.
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Door Thickness Compatibility Checker
See whether your door falls within a common residential thickness range.
Open calculatorTopics
Browse by job.
Topic
Cost
Budget parts and labor, schedule visits, and compare DIY against a locksmith quote.
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Door Measurement
Measure thickness, bore, backset, latch, strike, and handing before buying a replacement.
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Lock Changes
Count cylinders, split key groups, and price rekeying against replacement.
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Other Locks
Specialty checks such as mailbox lock fit.
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Security
Score entry hardening and fix structure before electronics.
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Smart Lock
Check retrofit fit, radio signal, battery life, and yearly battery cost before choosing a smart lock.
Open topicGuides
Understand the measurement before trusting the result.
Guide
Do Locks Affect Home Insurance?
What insurers ask, the documentation that pays, renewal timing.
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Locksmith Quote Negotiation Scripts
Negotiate lines, not totals: scripts that work.
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Photograph Your Lock for Identification
Five photos that identify nearly any lock.
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