Rekey vs. Change Locks: Which Do You Actually Need?

Most people searching this question already own working locks and simply want the old keys dead. That is a rekey. The rest have a lock that is worn, ugly, mismatched or not smart enough, and that is a replacement. The trick is knowing which doors fall into which bucket, because a single house often has both.

What is the difference between rekeying and changing locks?

Rekeying means a locksmith takes the cylinder out of your existing lock, swaps the small pins inside to a new combination, and cuts keys to match. The deadbolt, handle, latch and strike plate all stay exactly where they are. Old keys no longer turn the lock.

Changing locks means removing the hardware and installing new hardware. You get a new cylinder by default, plus whatever else the new lock brings: a different finish, a stronger bolt, a keypad, or a Wi-Fi radio.

Rekey vs. replace at a glance

For real numbers on each column, see what rekeying costs in San Diego.

How does rekeying actually work?

A standard pin-tumbler lock holds a row of five or six spring-loaded pin stacks. Each stack has a bottom pin cut to a specific height. The right key lifts every bottom pin exactly to the shear line so the cylinder can turn.

Rekeying replaces those bottom pins with a new set of heights. The locksmith then cuts keys to the new pattern. Nothing about the lock body changes, which is why it is fast and why the finish and fit on your door stay untouched.

Kwikset SmartKey locks skip the pin swap entirely. They rekey with a working key and a small tool, which we cover in our Kwikset SmartKey rekey guide.

When should you rekey?

You just bought or rented a home

Every previous owner, tenant, cleaner, contractor, dog walker and real estate agent may still hold a copy. Rekeying every exterior door on move-in day is the standard advice, and it is one of the most common jobs a locksmith does, booked through our new home rekey service. We wrote a full walkthrough in Should You Rekey After Buying a Home in San Diego? Arriving on military orders? The PCS lock checklist sequences the rekey with your move.

Keys are lost, stolen or never returned

If the lock works and you simply do not know where a key is, rekey. Replacing a perfectly good Schlage deadbolt because a key went missing is wasted money.

You want one key for every door

If your front door, back door and garage entry all share a keyway (all Kwikset, or all Schlage), a keyed-alike rekey puts them on one key without buying anything.

A tenant moved out

Landlords rekey between tenants as a matter of routine. It costs less than a set of new locks and takes minutes per unit. Our landlord turnover service is built around that schedule, and Rekeying Between Tenants in California covers the legal side.

When is replacement the right call?

The lock is worn, sticky or damaged

Keys that need jiggling, a bolt that does not throw fully, a cylinder that spins loose, or corrosion on coastal doors in Ocean Beach and Point Loma are signs the mechanism is done. New pins do not fix a worn cam or a bent bolt.

The keyways do not match

If the front door is Schlage and the back door is Kwikset, no amount of rekeying gives you one key. One of them has to change so both share a keyway. Usually you replace the cheaper one.

You want a higher security grade

Builder-grade locks on many tract homes in Chula Vista and Clairemont are often Grade 3, the lowest residential rating. Stepping up to a Grade 1 or Grade 2 deadbolt with a hardened bolt and a reinforced strike is a replacement, not a rekey.

You want a smart lock

A keypad or app-controlled lock is new hardware by definition. See our smart lock installation service for what is involved. The good news: most smart locks still have a keyway, so they can be rekeyed later like any other lock.

What about condos and HOAs?

In most San Diego condos the HOA controls the building entry and common-area doors, while you control the deadbolt on your unit door. That means you can usually rekey or replace your unit lock freely, though some associations require a specific finish or style to keep the hallway uniform. Check your CC&Rs before swapping to a keypad lock. We cover the details in HOA and Condo Lock Rules in San Diego.

Can you mix both on the same house?

Yes, and it is the most common outcome. A typical job in an older North Park Craftsman looks like this: rekey the original front-door deadbolt because it is solid brass and still tight, replace the rusted back-door knob that has been sticking for years, and rekey the garage side door to match the new key.

A good locksmith checks each door before quoting and tells you which doors need which. If someone recommends replacing everything without touching a door, get a second opinion.

How do you decide in two minutes?

1. Turn each lock with the key. Smooth and tight? Rekey candidate.
2. Sticky, loose, corroded or wobbly? Replacement candidate.
3. Want one key for all doors? Check whether the brands match. Matching keyways: rekey. Mixed: replace one.
4. Want a keypad or app control? Replacement with a smart lock.
5. Everything else, including new home, new tenant and lost keys, is a rekey.

Next step

If your locks turn cleanly and the only problem is who has a key, book a lock rekey and keep your hardware. If a door is fighting you every time you come home, our lock replacement and deadbolt installation page explains what a new lock involves and what it costs.