How to Change or Rekey Locks After Buying a Home
You have no idea who has a key to your new home. Previous owners, their kids, cleaners, dog walkers, contractors, neighbors who watered plants—any of them could still have a working copy. Changing or rekeying every exterior lock is the single most important thing you can do before you sleep in your new home, and it costs less than $250 for most houses.
Quick Summary
Time Required
1–2 hours
Difficulty
Easy — DIY friendly
Cost
$15–25 per lock rekey / $80–200 locksmith
Why Changing Locks Before Move-In Is Non-Negotiable
The lock-rekeying rule is simple: if you do not know every person who has ever held a key, assume every key is compromised. Sellers rarely track who they handed keys to over years of ownership.
The ghost key problem
Sellers typically hand you two or three keys at closing. The actual number of keys in circulation could be ten or more. House sitters, ex-partners, contractors, real estate agents, and lockbox services have all handled keys at some point. None of them have any legal obligation to return them.
Insurance and liability
If a burglary occurs with no signs of forced entry, some insurance policies will scrutinize the claim. Rekeying at closing creates a documented security reset and eliminates the "someone had a key" explanation from the equation.
Rekeying vs. Full Lock Replacement
Both options make old keys useless. The right choice depends on the condition of your existing hardware and whether you want to upgrade.
- Rekey ($15–25 per lock): A locksmith changes the internal pin configuration so old keys no longer work. Your existing hardware stays. Best for homes with modern, undamaged locks. A typical five-door home costs $125–225 with a mobile locksmith.
- DIY rekey kit ($12–20): Kwikset SmartKey and Schlage rekey kits let you rekey matching brand-family locks in under 10 minutes each. One kit rekeys every compatible lock in your house to a single new key.
- Full replacement ($40–300 per lock): Replace the entire lockset. Worthwhile if existing locks are worn, mismatched, or you want to upgrade to a higher security grade, a modern finish, or a smart lock.
- Same-key matching: Whether rekeying or replacing, ask for all exterior locks to work on a single key. This is the most convenient setup and costs no extra.
Smart Locks and Which Doors to Upgrade
Smart locks eliminate keys for your main entry points and let you issue time-limited codes to contractors, cleaners, and guests. The market has matured and reliable options start around $150.
Front door first
The front door is the highest-value place for a smart lock. You use it daily, it is where packages are delivered, and it is where guests and service providers arrive. A keypad smart lock like a Schlage Encode or August Wi-Fi handles 90% of real-world needs.
Keep a mechanical key on the back door
Unless you commit to smart locks throughout, keep at least one exterior door with a traditional keyed deadbolt. Battery failures happen, and a physical key is your guaranteed backup.
Do not forget the garage side door
The pedestrian door into your garage is the most commonly overlooked entry. It often has the cheapest hardware in the house and is hidden from street view, making it a prime target. Rekey or replace it with the same priority as your front door.
Keep One Old Key Until Everything Is Verified
The day of the changeover, test every new lock from both sides with every new key before you discard or hand over the old ones. Hold on to one old key in a safe location for 24–48 hours as insurance against a missed lock or a rekeying error.
- Verify the exterior-to-interior door: The door from your garage into the living space is an exterior-grade lock that many homeowners forget. It should be on your master rekey list.
- Check every deadbolt and every doorknob: Many doors have two locks. Rekey both. Some rekey kits only handle one hardware family at a time, so confirm compatibility before ordering.
- Mailbox and community locks: Cluster mailboxes, pool gates, and HOA amenities usually require separate re-keying through the association or USPS. Start those requests the first week.
Pro Tips
- •Schedule the locksmith for closing day: The moment you have keys is the moment to change locks. Book a mobile locksmith to meet you at the house the afternoon of closing so you never sleep on a compromised lock.
- •Ask for Grade 2 or better hardware: ANSI Grade 1 is commercial, Grade 2 is high-end residential, Grade 3 is builder-grade. Upgrading to Grade 2 doubles kick-in resistance for $30–50 more per lock.
- •Label spare keys discreetly: Never label spare keys with your address. Use a simple color code or a personal symbol. A labeled key lost in a parking lot becomes a free pass into your home.
- •Reinforce the strike plate: Swap the short screws in your deadbolt strike plate for 3-inch screws that bite into the wall framing. This $2 upgrade dramatically increases kick-in resistance on any door.
Frequently Asked Questions
Is rekeying as secure as replacing the entire lock?
Yes. Rekeying replaces the internal pin tumbler configuration so old keys no longer work, providing the same security as a new lock of the same grade. Replacement is only necessary if the existing lock is damaged, worn, or you want to upgrade to a higher security grade or smart lock.
How much does it cost to rekey a house?
A professional locksmith typically charges $15–25 per lock cylinder plus a service call fee of $50–100, so a five-door home runs $125–225 total. DIY rekey kits from Kwikset or Schlage cost $12–20 and let you rekey every matching lock in your home yourself.
Which doors should I prioritize?
Every exterior lock should be rekeyed before you spend a night in the home. Do not forget garage side doors, basement walk-outs, and the interior door from the garage to the house. These are frequently overlooked but provide easy access to anyone holding an old key.
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