You just took possession, and somewhere out there are keys to your house held by the previous owners, their kids, a cleaner, a dog walker, a contractor and whoever else accumulated one over the years. Nobody kept a list. This is the single most common reason people call a locksmith, and the fix is usually cheaper than expected.
The short version
Rekeying changes the internal pins in your existing lock so old keys no longer work. The hardware stays on the door. $25 to $50 per lock, plus a service call.
Replacing installs entirely new hardware. $80 to $250 per lock installed, depending on what you’re putting on.
If your locks work properly and you’re happy with how they look, rekey. If they’re worn, damaged, or you want something better, replace.
How rekeying actually works
Inside a standard pin tumbler lock is a row of spring-loaded pins of varying heights. The correct key pushes each pin to exactly the right level, letting the cylinder turn.
Rekeying means removing the cylinder, swapping those pins for a different combination of heights, and cutting a new key to match. The lock body, the finish, the strike plate, the screws in your door — all stay exactly where they are. A technician does it in five to ten minutes per lock.
The result is functionally identical to a new lock as far as security goes. Every previously issued key becomes a piece of scrap metal.
When rekeying is the right choice
You just bought the house. The most common scenario, and rekeying handles it completely. Do it before you move furniture in, not after.
A key went missing. Lost keys are worse than they sound if the keyring also had anything identifying your address.
A tenant moved out. Rekeying between tenancies is standard practice and cheap enough to do every turnover.
A relationship ended. Same logic, no explanation needed.
A contractor had access. Most are entirely trustworthy. Keys still get copied, lent, and left in trucks.
You want one key for every door. If your front, side and garage entry doors all take different keys, they can usually be rekeyed to match — provided they’re the same brand and keyway. This is one of the most satisfying $150 you can spend on a house.
When to replace instead
The lock is worn or sticking. If the key needs jiggling, the mechanism is worn internally and rekeying won’t fix that.
There’s visible damage. Pry marks, a bent cylinder, or a cracked housing means the lock has already been tested by someone.
It’s a low-grade lock. Builder-grade hardware on new construction is often the cheapest thing that met code. Rekeying a weak lock leaves you with a weak lock.
You want a higher security grade. ANSI Grade 1 is commercial-level and the best residential choice; Grade 2 is solid; Grade 3 is minimum. Most builder hardware is Grade 3.
You want smart locks. Keypad and app-controlled locks let you issue and revoke codes without touching the hardware again — genuinely useful for rentals, cleaners and kids who lose things.
Mismatched brands across doors. If your doors carry three different manufacturers, they can’t be keyed alike without replacing at least some of them.
Security grades in plain terms
| Grade | Built for | Typical use |
|---|---|---|
| Grade 1 | Highest residential/commercial standard | Front entry doors worth protecting properly |
| Grade 2 | Solid mid-range | Side and rear entries |
| Grade 3 | Minimum acceptable | Interior doors, low-risk applications |
The grade is stamped or listed on the packaging. On an existing lock, a locksmith can usually identify it on sight.
What actually protects a door
This gets overlooked constantly: the lock is rarely the weak point.
Most residential break-ins involving force are kick-ins, and the door usually fails at the strike plate — the metal plate on the frame where the bolt lands. Factory strike plates are held by two three-quarter-inch screws that grip nothing but soft trim.
Upgrading to a reinforced strike plate with three-inch screws that reach the wall stud costs about $15 and does more for your door than a $200 lock. Any locksmith worth calling will suggest it. If yours doesn’t, ask.
The other common weakness is a deadbolt with less than one inch of throw, or a hollow-core door on an exterior opening. Neither is fixed by better locks.
What a whole-house job costs
A typical four-door house after closing:
- Service call: $60 to $100
- Rekeying four locks: $100 to $200
- Two new keys per lock: usually included
- Total: roughly $160 to $300
Replacing the same four locks with mid-grade hardware runs $400 to $900 installed. Add a smart lock on the front door and budget another $200 to $400.
A common middle path: rekey the side and rear doors, replace the front with something better. You get the security upgrade where it’s most visible and most likely to be tested, without paying to replace hardware nobody sees.
Frequently asked questions
Can I rekey a lock myself? Rekey kits are sold for common brands and work if you’re patient and the lock matches the kit. The pins are tiny, the springs launch themselves across the room, and a mistake leaves you locked out of your own house. For one or two locks the savings over a professional visit are thin.
Does rekeying weaken the lock? No. The pins are consumable components designed to be changed. A properly rekeyed lock is mechanically identical to how it left the factory.
How many times can a lock be rekeyed? Effectively unlimited, as long as the mechanism is in good condition. Landlords rekey the same locks for decades.
Can all my locks be keyed alike? Usually, if they share a brand and keyway. Mixed brands need at least one cylinder swapped to match. A locksmith can tell you in about thirty seconds of looking.
How long does it take? Five to ten minutes per lock. A four-door house is done inside an hour, including cutting the new keys.
Should I rekey a brand new build? Yes. Construction keys circulate widely during a build, and the “master” that the trades used may still work. Most builders rekey at handover, but confirming costs nothing and assuming costs plenty.