Rekeying vs Changing Locks: What's the Difference and Which One Do You Actually Need?

If you've recently moved into a new home, ended a tenancy, lost a key, or had someone move out of your property, you've probably been told that you need to do something about your locks. The advice you receive in that situation tends to fall into one of two camps: rekey the locks, or change them entirely. The problem is that these two terms are often used interchangeably, even though they refer to meaningfully different procedures with different costs, different outcomes, and different situations where each one makes sense.

Making the wrong choice doesn't just cost you money. It can leave you with a false sense of security or lead you to spend significantly more than the situation actually requires. Understanding the difference clearly — and knowing which one applies to your circumstances — is the kind of practical knowledge that pays off when it matters most.



This guide explains exactly what rekeying and lock replacement each involves, when one is the right call over the other, and what questions to ask a locksmith before committing to either.

What Does Rekeying a Lock Actually Mean?

Rekeying is a process that changes the internal configuration of an existing lock so that the old keys no longer work and a new key is required to operate it. The lock body, the hardware, and the installation all stay exactly as they are. What changes is the arrangement of the pins inside the lock cylinder.

Every pin tumbler lock — which covers the vast majority of residential locks in Melbourne — operates by using a set of spring-loaded pins that align at a specific height when the correct key is inserted. That alignment is what allows the cylinder to rotate and the lock to open. Rekeying involves a locksmith disassembling the cylinder, removing those pins, and replacing them with a new set that corresponds to a different key cut. The result is a lock that functions identically to before, but responds only to the new key.

It is a precise job that requires the right tools and knowledge of the specific lock being worked on, but it is generally faster and less expensive than full replacement because the hardware itself is not being changed. One of the practical advantages of rekeying is that a locksmith can often rekey multiple locks across a property to operate on a single new key — a process known as keying alike — which is a significant convenience for homeowners with several entry points.

What Does Changing a Lock Mean?

Changing a lock, or lock replacement, means removing the existing lock hardware entirely and installing new hardware in its place. This includes the cylinder, the lock body, and, in some cases, the handles, plates, and associated fittings, depending on the type of lock and the scope of the job.

The result is a completely new lock mechanism that has no relationship to the old one. Old keys are rendered useless not because the internal configuration has been changed, but because the entire lock has been replaced with a different unit.

Lock replacement is a more involved job than rekeying and carries a higher cost, primarily because of the hardware involved. The total cost depends on the type and grade of lock being installed — a basic deadbolt is considerably less expensive than a high-security cylinder from a premium brand — as well as the complexity of the installation.

The Key Differences Side by Side

The distinction between the two comes down to a few core factors that are worth understanding clearly before you speak to a locksmith.

What changes: Rekeying changes the internal pin configuration of an existing lock. Replacement changes the entire lock mechanism.

What stays the same: With rekeying, the lock hardware, the door preparation, and the installation all remain unchanged. With replacement, everything is new.

Cost: Rekeying is generally the less expensive option because no new hardware is required. Replacement involves the cost of the new lock on top of the labour.

Outcome for security: Both options render old keys useless, which is the core security objective in most situations. The difference is that replacement also allows you to upgrade the grade or type of lock, which rekeying does not.

Time on-site: Rekeying is typically a faster job. Replacement takes longer, particularly if door preparation is required for a different lock type.

When Rekeying Is the Right Choice

Rekeying is the appropriate solution in a wide range of common situations, and it is often the option that homeowners don't consider because they default to assuming replacement is necessary.

You've moved into a new home

This is one of the most common and most important situations for rekeying. When you take possession of a property, you have no reliable way of knowing how many copies of the existing keys are in circulation. Previous owners, tradespeople, real estate agents, and neighbours may all have had keys cut at some point. Rekeying every entry point on the property immediately after settlement or handover is a straightforward, cost-effective way to ensure that only you hold a working key.

A tenancy has ended

If you're a landlord and a tenant has vacated, rekeying the property before a new tenant takes possession is not just good practice — it protects both you and your incoming tenant from any security exposure created by keys that weren't returned or were copied during the tenancy.

A key has been lost

A lost key is a security risk if there is any possibility that it has been found by someone who could identify which property it belongs to. Rekeying removes that risk entirely without the expense of replacing hardware that is otherwise in perfectly good condition.

Someone who held a key no longer should

Relationship breakdowns, the end of a house-sharing arrangement, a falling out with someone who had access to your home — these are all situations where rekeying quickly and cleanly resolves a security concern without unnecessary cost.

The existing lock hardware is in good condition

If the lock is relatively new, functioning smoothly, and is an appropriate grade for the property, there is no reason to replace it simply to address a key control issue. Rekeying achieves the same security outcome at a fraction of the cost.

When Lock Replacement Is the Right Choice

There are situations where rekeying is not sufficient or appropriate, and full replacement is the correct recommendation. A reputable locksmith will identify these situations and explain the reasoning clearly.

The lock is old or worn

A lock that is stiff, difficult to operate, or showing signs of wear may be approaching the end of its serviceable life. Rekeying a worn lock addresses the key control issue but does nothing for the underlying mechanical condition. In this case, replacement makes more sense as a long-term investment.

The lock has been damaged

A lock that has been forced, drilled, or damaged in a break-in attempt should be replaced, not rekeyed. The integrity of the mechanism may be compromised in ways that are not always visible, and operating a damaged lock creates an ongoing security risk.

You want to upgrade your security level

Rekeying works with the existing lock, which means it cannot improve the grade or security rating of the hardware. If your property has basic, low-grade locks and you want to upgrade to a higher-security option — a quality deadbolt, an Abloy or Mul-T-Lock cylinder — replacement is the only way to achieve that.

The lock type is being changed

If you're moving from a knob lock to a deadbolt, adding a second lock point, or changing from a single to a double cylinder configuration, replacement is required by definition. Rekeying cannot change the physical type of lock in place.

The lock has failed mechanically

A lock that no longer operates correctly — a deadbolt that won't extend fully, a latch that doesn't engage — needs replacement, not rekeying. Rekeying addresses only the key configuration, not the mechanical function.

Questions Worth Asking Before You Commit

When you call a locksmith to discuss either option, a few straightforward questions will help you make a confident decision.

Ask what condition the existing lock is in and whether it warrants replacement on its own merits. Ask whether rekeying will achieve the same security outcome as replacement in your specific situation. Ask whether the locks across the property can be rekeyed to a single key if that's a priority for you. Ask for a clear quote covering labour and any parts before work begins.

A trustworthy locksmith will answer all of these questions plainly and recommend the option that actually fits your situation — not the one that generates the higher invoice.

What About Master Key Systems?

For homeowners with multiple entry points, landlords managing several properties, or anyone who wants to simplify key management, a master key system is worth understanding alongside the rekeying conversation.

A master key system allows individual locks to be operated by their own unique key while also being operable by a single master key. This is common in commercial settings but is increasingly relevant for residential properties with multiple entry points — garages, outbuildings, secondary dwellings — where carrying multiple keys becomes impractical.

Setting up or expanding a master key system is a job for a licensed locksmith with experience in key system design. It involves careful planning of the pin configurations across all locks in the system, and it is something that should be established correctly from the outset rather than retrofitted piecemeal.

Getting the Right Advice for Your Specific Situation

The honest answer to the question of whether you need rekeying or replacement is that it depends on the condition of your existing locks, your reason for making the change, and what security outcome you're trying to achieve. Both options have their place, and neither is universally the right answer.

At Malvern Lock Service, we've been helping homeowners across Malvern, Toorak, South Yarra, Armadale, Hawthorn, Camberwell, Glen Iris, Prahran, St Kilda, and surrounding Melbourne suburbs make exactly this kind of decision for over 35 years. We'll assess the condition and grade of your existing locks, understand what prompted the change, and recommend the option that actually serves your security needs — with clear pricing before any work begins.

Not Sure Whether to Rekey or Replace? We Can Help.

Call Malvern Lock Service on 0477-615-507 or contact us here to speak with a licensed locksmith about your specific situation. We'll give you a straight answer and a clear quote before we touch anything.