Rekey or Replace? How to Decide After Losing Your Keys

Lost your keys, moved into a new home, or just uneasy about who might still have a copy? You have two real options: rekey the existing lock, or replace it entirely. Both restore your security, but they solve slightly different problems, cost different amounts, and suit different situations. Here's how to work out which one you actually need.

In this guide:

• What's the difference between rekeying and replacing?
• When rekeying makes the most sense
• When replacing is the better option
• Cost comparison: rekey vs replace
• Moving into a new home? Do this first
• What if you manage multiple properties or units?
• How rekeying actually works, step by step
• Signs your lock needs replacing, no matter what
• Frequently asked questions

What's the Difference Between Rekeying and Replacing?

This is one of the most common questions homeowners across Pretoria and Centurion ask after a lost key, a break-in, or simply moving into a new property, and understanding the distinction up front makes the rest of the decision much easier.

Rekeying means a locksmith changes the internal pin configuration of your existing lock so that old keys no longer work, and a new key is cut to match. The lock hardware itself — the deadbolt, the housing, the strike plate — stays exactly the same.

Replacing means removing the entire lock mechanism and fitting a brand new one, often with a different brand, grade, or style. This is necessary when the lock itself is damaged, outdated, or simply not secure enough for your needs.

Both approaches achieve the same core outcome: any key that used to open your door no longer does. The right choice depends on the condition of your current hardware and why you need the change in the first place.

When Rekeying Makes the Most Sense

Rekeying is usually the faster, more cost-effective option when:

• The existing lock is in good working condition — no rust, sticking, or wear.
• You've lost a key or suspect a copy is floating around, but the lock itself is fine.
• A tenant has moved out and you want to secure the property quickly and affordably.
• You like your current hardware and just want peace of mind that old keys won't work anymore.

Our reliable locksmith technicians can usually rekey a standard residential lock on site in well under an hour, with a fresh set of keys cut on the spot.

When Replacing Is the Better Option

Replacement becomes the right call when:

• The lock is old, worn, sticking, or shows signs of a previous forced entry attempt.
• You want to upgrade to a higher security grade deadbolt or a smart lock.
• The lock brand no longer has parts or key blanks readily available.
• You're renovating and changing your door hardware anyway.
• A break-in has already occurred and the lock mechanism itself was damaged.

If you're dealing with a recent break-in, it's worth reading our guide on break-in prevention for Pretoria and Centurion homes, which covers upgrades worth considering at the same time.

Cost Comparison: Rekey vs Replace

Budget is often the deciding factor once security needs are equal between the two options. As a general rule:

1. Rekeying is cheaper because it reuses your existing hardware — you're paying mainly for labour and new keys.
2. Replacing costs more because it includes the price of a new lock mechanism, plus installation.
3. If you have multiple doors using the same key (a common setup on older homes), rekeying all of them together is usually more cost-effective than doing it one door at a time.

A residential locksmith visit will typically diagnose your specific lock and give you a clear price for both options on the spot, rather than pushing you toward the more expensive choice by default.

Moving Into a New Home? Do This First

If you've just bought or rented a new property in Pretoria, Centurion, or Johannesburg, don't assume you have every key that exists for that property. Previous owners, tenants, agents, cleaners, or contractors may still hold working copies. The safest move is to rekey (or replace, if the locks are old) every external door before you fully settle in — not after something goes wrong.

We cover this in more depth in our moving house locksmith checklist, which walks through everything worth doing in your first week in a new home.

What If You Manage Multiple Properties or Units?

Landlords, body corporates, and property managers dealing with multiple units often benefit from a master key system rather than rekeying units individually every time a tenant changes. A master key setup lets you (or your caretaker) access common areas or specific units when needed, while each tenant still has their own unique key that doesn't work anywhere else. It's a bigger upfront project, but it saves a huge amount of admin over time. Our full master key systems explained guide goes into more detail on how these hierarchies are structured and planned.

How Rekeying Actually Works, Step by Step

If you've never had a lock rekeyed before, the process is quicker and less invasive than most people expect:

1. The locksmith removes the lock cylinder from the door — the deadbolt housing and door hardware itself stay in place.
2. The cylinder is opened and the existing pins, which match your old key, are removed.
3. New pins, matched to a fresh key code, are installed in their place.
4. The cylinder is reassembled and refitted into the existing hardware.
5. New keys are cut on the spot and tested in the lock to confirm smooth operation.
6. Old keys are tested against the lock to confirm they no longer work.

The whole process typically happens on your doorstep, without removing the door itself or leaving your home insecure at any point during the visit.

Signs Your Lock Needs Replacing, No Matter What

Regardless of why you're considering a change, some signs point specifically toward replacement rather than rekeying:

• Visible rust or corrosion inside the keyway or on the bolt itself.
• A key that requires jiggling or force to turn, even when it's a known-good key.
• A deadbolt that doesn't fully extend into the door frame when locked.
• Loose screws or a wobbly handle that keeps coming undone despite tightening.
• A lock more than 15-20 years old on an exterior door, where security standards have moved on considerably since it was installed.

If any of these describe your current lock, it's worth asking your locksmith for a replacement quote alongside a rekey quote, so you can compare properly before deciding.

Frequently Asked Questions

Can any lock be rekeyed?

Most standard pin tumbler locks can be rekeyed. Some older, damaged, or very low-quality locks may not be worth rekeying and are better replaced outright — your locksmith will be able to tell you on site.

How long does rekeying take?

A standard residential rekey usually takes 20 to 45 minutes per lock, depending on the hardware and how many doors are being done.

Is rekeying as secure as replacing the whole lock?

Yes, provided the lock hardware itself is in good condition. Rekeying changes the internal pins, so old keys genuinely stop working — the security outcome is the same as a full replacement in that respect.

Should I rekey after buying a second-hand security gate?

Yes. The same logic applies to gates, garages, and outbuildings as it does to your front door — anything with a lock should be treated as potentially compromised until it's rekeyed or replaced.

Do all the locks on a property need to be rekeyed to the same key?

Not necessarily, but it's usually far more convenient. Keying every external door alike (so one key opens them all) is a common request during a rekey, and typically costs very little extra compared to rekeying each lock separately.