Keys wear out because metal rubs on metal every time you use them. Most house keys are brass or a softer alloy, so the cuts slowly round off until the key sticks, needs jiggling or stops working. A fresh key cut from the code or a less-worn spare is often the fix.
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Get the Lost-a-Key Guide →$4.99 · instant PDF downloadWhy keys wear out
Most people think keys are hard steel and last forever. In reality, many residential keys are brass or softer alloys, because they are easier to cut and create less wear on the lock itself.
- Every time a key slides into a lock and turns, metal rubs against metal.
- Over thousands of uses, tiny amounts of material disappear from the peaks and valleys of the key.
- The changes are usually too small to see, but inside a lock those tiny differences change how the key lifts the pins. See how locks work for the pins and shear line.
- Eventually the key may stick, work inconsistently or stop working altogether.
Bill’s longer walkthrough of a key that always worked and then stopped. Watch on YouTube.
Signs your key may be wearing out
- The key works sometimes but not every time
- You have to jiggle the key
- The key sticks going in or coming out
- You need extra force to turn the lock — compare this symptom with the hard-to-turn deadbolt guide before assuming the key alone is worn
- A spare key works better than the original
Can a worn key be fixed?
- Try a less-worn spare. If it works smoothly, the original key is the likely problem.
- Get a fresh key cut from the original key code or from that less-worn spare, not from the worn key.
- If the lock is worn too, a locksmith may recommend rekeying, repairing worn parts or replacing damaged hardware. Compare rekey or replace.
Many people assume the lock has failed when the real problem is years of gradual wear on the key itself. If the key quit suddenly instead, read why keys stop working.
Related locksmith guides
Ready to keep learning? Return to the Beginner Locksmith Path and follow the lessons in order.
Before you buy parts or book a locksmith
Use the free lock-check checklist to record your symptom, hardware and measurements. Keep it beside the matching repair guide so you buy for the problem you actually have.
Printable guides from Bill
Keys giving you trouble?
If a key is worn, bent or missing, these checklists help you work out what to replace and who might still have access.
Printable PDFs from Kwikpick Lock and Safe. Instant download, checkout by Gumroad. More for new homeowners on our new homeowner page.
Parts and tools for this problem
Start with the matching checks in Bill’s field guides. Buy only after you identify your hardware and the cause.
The correct spare key before a replacement lock
A known working spare can help separate key wear from a lock problem. Do not order a cylinder or spray a product into it based on resistance alone.
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