Home lock calculator
Mailbox Lock Replacement Fit Checker
Screen a standard residential mailbox lock replacement before you buy.
Result
Cam deviation from 1-1/4 in
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Common cam size (1 = yes)
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Controlled box, no DIY (1 = yes)
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Formula
Calculation logicCluster mailbox locks may require the property manager or USPS process. Do not force a replacement.
Mailbox Locks and Entry Hardening Order
Mailbox rules first
Cluster (NBU) and apartment panels are USPS- or manager-controlled: do not buy DIY parts. Standalone and wall boxes use a 5-pin cam lock matched to cam length; damaged holes need a repair plate.
Harden in this order
- Full 1-in deadbolt throw on every entry.
- 3-in strike screws into the stud.
- Lighting on every dark entry.
- Hinges, glass film, then electronics.
A smart lock on a hollow door is theater. Structure first, electronics last.
Verify before you buy
- Identify box type before buying parts
- Measure cam and hole condition
- Never force a cluster door