Lost house keys are a homeowner's worst nightmare—especially when you're standing on the porch at midnight or realizing a set went missing weeks ago. The big question isn't just how to get back inside; it's whether you should rekey your existing locks or replace them entirely. Understanding the difference could save you hundreds of dollars and give you genuine peace of mind about who might have access to your home.
The Core Difference: Rekey vs. Replace
Rekeying changes the internal pins in your existing lock cylinder so that your old keys no longer work. A locksmith removes the plug (the part that turns when you insert your key), replaces the pins, and reassembles it—typically taking 15–30 minutes per lock. Replacement means installing a completely new lock body, deadbolt, or hardware, which is faster but more expensive.
Think of rekeying as reprogramming your lock's DNA; replacing is buying new locks altogether.
When Rekeying Makes Sense
Rekeying is the smart financial choice in most lost-key scenarios. You'll typically pay $15–$25 per lock for the service, so rekeying three entry doors costs roughly $45–$75. It's ideal when:
- You lost keys recently and want to prevent anyone who found them from entering
- Your locks are modern, well-maintained, and function smoothly
- You're staying in the home long-term and aren't concerned about compatibility with a new aesthetic
- You want a quick turnaround—many locksmiths can rekey locks same-day
For example, if you lost a single house key to your front and back doors, a residential locksmith can rekey both in under an hour for under $50.
When Replacement Is the Better Option
Replace your locks when rekeying doesn't address the underlying problem or when the locks themselves are compromised. Consider replacement if:
- The locks are old or damaged. Locks over 10–15 years old may have worn pins or springs that don't hold rekeying effectively. Replacement typically runs $100–$300 per lock, installed.
- You're unsure how many people have copies. If your keys disappeared during a break-in, a rental transition, or a messy separation, replacement offers cleaner assurance. Rekeying only helps if the locksmith can guarantee no other copies exist.
- You want to upgrade security. Modern smart locks ($150–$400 installed) or high-security deadbolts ($80–$200) provide better protection than rekeying an old basic lock.
- Multiple locks need work. If you're rekeying five or more locks, the labor costs approach replacement pricing anyway.
- You're selling or renting the property. Buyers and tenants often expect new locks or at minimum a complete rekey with fresh master keys.
Step-by-Step: What to Do Right Now
- Verify you actually lost the keys (check coat pockets, cars, and bags first)
- Call a licensed residential locksmith and describe your situation—lost vs. stolen makes a difference in recommendations
- Ask for a quote on both rekeying and replacement before committing
- Get the estimate in writing, including any service fees or trip charges (typically $50–$100)
- Ask how long the job takes—you'll want a realistic window for your schedule
What Locksmiths Look For
A good residential locksmith will physically inspect your locks before recommending a solution. They'll check:
- Lock cylinder condition and wear
- Whether the lock is a standard pin-tumbler or a higher-security model
- If the door frame is solid (no point rekeying if the frame needs repair)
- Manufacturer and age of existing hardware
This inspection usually adds 10–15 minutes but prevents expensive mistakes. If a locksmith quotes you over the phone without seeing your locks, get a second opinion.
Finding the Right Locksmith
Verify that any locksmith is licensed in your state and carries liability insurance. Mercoly helps you compare and find trusted residential locksmiths in one place, so you can review credentials, read customer feedback, and get multiple quotes without cold-calling around town.
Ask each locksmith:
- How long they've served your area
- Whether they guarantee their work
- If they handle rekeying and replacement equally well
Frequently Asked Questions
Q: Will rekeying my lock work with my existing house keys? No—rekeying specifically invalidates your old keys. After the service, only the new keys the locksmith provides will work with that lock.
Q: Can I rekey a smart lock or electronic deadbolt? Not in the traditional sense. Electronic locks are replaced rather than rekeyed; the locksmith will remove the old unit and install a new one with new credentials ($200–$400 installed, depending on the model).
Q: How quickly can a locksmith arrive if I'm locked out? Most locksmiths offer emergency or same-day service; response times range from 30 minutes to 2 hours depending on location and demand. After-hours calls typically cost 1.5–2x the standard rate.
Compare quotes from licensed residential locksmiths in your area to get the best price and service for your situation.