Key Takeaways: Rekeying is almost always cheaper upfront, but replacing locks offers long-term value and security upgrades. The right choice depends on your lock’s condition, your security goals, and whether you’re dealing with a lost key or a simple tenant turnover. We’ll break down the real costs—including the ones you don’t see on the invoice.
So, you’ve got a set of keys you don’t trust anymore. Maybe a roommate moved out, you bought a house, or you just can’t remember who all has copies of the garage key. The immediate question is a practical one: do you just rekey the locks, or swap them out entirely? Everyone’s looking to save a buck, but the cheapest option right now isn’t always the smartest spend over the long haul.
Let’s get the basic answer out of the way.
Rekeying is the process of changing the internal pins of an existing lock so that it works with a new key. The lock hardware itself—the doorknob, deadbolt, and its exterior shell—stays put. A locksmith takes it apart, replaces the pin tumblers, and tests the new key. It’s a fast, skilled job.
Replacing locks means removing the entire lock hardware and installing a brand new one. You get new keys, new hardware, and often, a chance to upgrade the security level or style of the lock itself.
The upfront cost difference is straightforward. For a standard residential door, rekeying a lock might cost you between $20 and $50 per cylinder, while a new, decent-quality deadbolt can run $50 to $150 plus installation. So, on paper, rekeying wins on price. But that’s just the entry fee. The real decision happens when you look past the invoice.
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When Rekeying Makes Perfect Sense (And When It’s a Band-Aid)
We rekey locks all the time, and in the right situation, it’s the undisputed champion of cost-effectiveness.
The classic scenario is tenant turnover in a rental property. You have no reason to believe the locks are faulty; you just need to ensure the previous tenant’s keys no longer work. Rekeying the entire property in an hour is a no-brainer. Same goes for moving into a newly purchased home—you have no idea how many copies of the key the previous owners made for neighbors, family, or contractors. A full rekey gives you peace of mind and control.
But here’s the catch we see constantly: rekeying only makes sense if the lock you’re keeping is worth keeping. If the lock is old, wobbly, rusted, or a builder-grade model that was flimsy to begin with, you’re just perpetuating a weak link. We’ve been to homes in older Allston neighborhoods where the original locks are 30 years old. They work, but the metal is worn, the bolt throw is sluggish, and the keyway is loose. Rekeying that lock gives you a new key for a tired mechanism. It’s like putting new tires on a car with a failing transmission.
The Hidden Value in a Full Lock Replacement
This is where the math changes. Replacing a lock isn’t just about new keys; it’s an opportunity to solve other problems. Maybe the existing deadbolt is too short for the door frame, a common issue in older Boston triple-deckers where doors have been replaced but hardware wasn’t updated. A new lock lets you install one with a longer bolt for better resistance against kick-ins.
More importantly, it lets you upgrade security levels. That old lock might be a Grade 2 or even a Grade 3 (residential grade). A new lock can be a Grade 1—commercial grade—which means it’s been tested to withstand significantly more force, cycles, and manipulation. You’re not just changing keys; you’re fortifying the entry point.
We also recommend replacement if you want to achieve key uniformity—having one key for all your doors. If your current locks are from different brands (a Kwikset on the front, a Schlage on the back, and a mystery brand on the garage), they can’t be rekeyed to the same key. Replacing them with a matched set from one brand solves that forever.
The Cost Breakdown Beyond the Service Call
Let’s talk real numbers. The price isn’t just parts and labor; it’s time, risk, and future hassle. Here’s a comparison based on a typical single-family home with three exterior doors.
| Consideration | Rekeying (3 Doors) | Replacing (3 Mid-Grade Deadbolts) | The Trade-Off |
|---|---|---|---|
| Upfront Parts & Labor | $90 – $150 | $250 – $450+ | Rekeying wins on immediate cash outlay. |
| Security Level | Stays the same. | Can be upgraded significantly. | Replacement lets you address known weaknesses. |
| Hardware Condition | Perpetuates wear, wobble, or rust. | Everything is new, tight, and warrantied. | New hardware feels and functions better. |
| Key Convenience | New keys, but multiple keys if locks differ. | Can be keyed alike for one master key. | Huge quality-of-life win for replacement. |
| Long-Term Value | Lower, as hardware will eventually fail. | Higher, adding security and property value. | Replacement is an investment; rekeying is maintenance. |
| DIY Potential | Low. Requires specific tools & skill. High risk of ruining the lock. | Moderate. Requires basic tools & careful installation. | A botched DIY install can compromise security more than an old lock. |
“Can’t I Just Do This Myself?”
You can buy a rekeying kit at the hardware store for $15. I’m not going to tell you it’s impossible. I am going to tell you what we see when homeowners attempt it: springs and tiny pins flying across the room, cylinders reassembled incorrectly so the key works but the thumbturn doesn’t, or locks that seem fine but are now more vulnerable to picking because the pins aren’t seated right.
The risk isn’t just a broken lock. It’s creating a false sense of security. With replacement, the challenge is aligning the new hardware perfectly with the existing holes in the door and frame. Get it wrong, and the deadbolt won’t throw smoothly, the strike plate is misaligned, and you’ve created a new point of weakness. For most people, the time spent researching, purchasing, and potentially fixing mistakes outweighs the cost of a professional doing it in a fraction of the time, with a guarantee. If you’re near a busy area like the Harvard Ave corridor, the peace of mind knowing it’s done right is worth the call to a local pro like us at Elite Locksmith.
So, What’s the Final Verdict?
Stop asking which is cheaper. Start asking which is more appropriate.
Choose to rekey when:
- The existing hardware is in good, solid condition.
- You’re simply removing access (tenant move-out, lost keys).
- All locks are the same brand and can be keyed alike.
- Budget is the primary and immediate constraint.
Choose to replace when:
- The locks are old, worn, loose, or low-quality.
- You want to upgrade your security level (especially to Grade 1).
- You have a mismatched set and desire one-key convenience.
- You’re already noticing issues like sticking, jiggling, or rust.
In our experience, most homeowners who opt for rekeying end up replacing those same locks within a few years as the hardware continues to age. Those who replace, especially with a quality product, rarely think about their locks again for a decade or more. The initial investment spreads out over years of reliable, superior security.
It boils down to this: rekeying changes the access. Replacing changes the access point. One is a quick fix; the other is a considered upgrade. Figure out what you really need, and the cost will take care of itself.
