Many locks don’t need replacing. If the hardware still works and you just want old keys to stop working, a rekey changes the pins so a new key runs the same lock. Replacement makes sense when the hardware is broken, worn out or wrong for the door.
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A real rekey on a Defiant deadbolt with no key: what changes inside, and why it costs less than new locks.
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Rekeying changes key control; replacement changes hardware
Rekeying and replacing a lock solve different problems. Rekeying changes which key operates a serviceable cylinder while the usable hardware stays in place. Replacement changes some or all of the hardware because its condition, function, compatibility, appearance or security level no longer fits the need.
Start with the result you want. To cancel old keys after a move or staff change, a compatible rekey may handle key control. If the lock is damaged, unreliable, wrong for the opening or can’t provide the function you need, replacement may be the better option.
When rekeying may fit
- The existing hardware works correctly and is in serviceable condition.
- The main concern is who may still have an old key.
- The cylinder is designed to be serviced and supports the keying plan you want.
- The door, latch, bolt, strike and mounting are otherwise right for the opening.
When replacement may fit better
- The hardware is broken, badly worn, corroded, missing parts or no longer dependable.
- You need a different function, grade, accessibility feature, key system or cylinder format.
- The lock can’t be serviced economically, or the manufacturer no longer supports the parts.
- The opening has fire, egress, code, electrified or access-control requirements that need verified compatible hardware.
Why people replace locks unnecessarily
Many people think a lock problem means the whole lock has failed. Locksmiths often see perfectly good hardware that only needs a rekey. A rekey changes the internal pin configuration so the lock works with a different key while the existing hardware stays.
Bill’s short walkthrough on why new owners don’t always need new hardware. Watch on YouTube.
What locksmiths actually change during a rekey
- The lock cylinder is removed.
- Internal pins are replaced or rearranged.
- The pin stack is matched to a different key.
- The lock is tested for smooth operation.
- In many cases, the existing hardware stays installed.
Start with what rekeying means, then use the rekeying training hub for the full process. Review how locks work and Common Lock Problems before assuming a key symptom means the whole lock must go. Have a Kwikset SmartKey? It uses its own SmartKey reset process.
What a useful estimate should clarify
A good recommendation explains your goal, the hardware’s condition, whether the cylinder is serviceable, which old keys will stop working, which new keys are included, and how the result will be tested. Uncertain authorization, unfamiliar systems, restricted keys and code-sensitive openings need checking before work begins.
Just bought a home? Rekeying your exterior locks is on our new homeowner lock checklist. Real estate agents can also give buyers a personalized closing-gift security packet that walks them through it.
Related locksmith guides
Want more about locks, tools and real locksmith work? Visit LocksmithBlueprint.com for guides and videos.
Locksmith Blueprint Learning System
Watch It. Read It. Do It.
Watch It
Use the existing video to observe why a change in key control does not automatically require new hardware.
Read It
Compare the serviceability, function, condition, compatibility, and security questions behind the decision.
Do It
Create a two-column decision sheet for an owned practice lock: reasons to preserve it and reasons replacement might be justified. Do not disassemble unfamiliar hardware.
What does a rekey cost? See how much it costs to rekey a lock in 2026: service call, per-lock price and how to keep it cheap.
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
After you rekey
Rekeying changes who can get in. These printable checklists cover what comes next: spare keys, codes and the other doors.
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.
A cylinder-compatible rekey kit
Bill’s rekeying demonstration uses a pinning kit, plug follower, tweezers and small screwdrivers. Match the cylinder, keyway and pinning chart before buying.
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