The short answer
Rekey when the problem is who has a key. Replace when the problem is the lock itself.
That single sentence resolves most cases. You have just bought a house, a tenant has moved out, builders had access, a keyring went missing, a relationship ended, those are all key problems. The hardware on your door is fine. Rekeying changes the pins inside so a new key works and every old one stops, and it costs a fraction of new hardware because you are reusing what you already own.
You replace when the lock is worn out, damaged, or was never adequate for the door, a knob lock doing duty as the only lock on an exterior door, for example. You also replace when you want a different function, such as a keypad or a smart lock, because that is a change to what the lock does rather than which key it accepts.
There is a third answer people almost never hear, and it is the cheapest of the three: sometimes neither. A lock that has become stiff or unreliable is often a worn key or a misaligned door, and a fresh key cut to code or a strike adjustment fixes a lock nobody needed to touch.
The long answer
What a rekey actually changes.
Understanding the mechanism is what lets you judge a quote instead of accepting it.
Inside a pin tumbler cylinder are pairs of pins in vertical channels, held down by springs. The lower pin of each pair is cut to a specific height. The correct key lifts every pair to exactly the point where the join between them lines up with the shear line, the boundary between the rotating plug and the fixed housing. When all of them align, the plug turns. When one does not, nothing happens.
Rekeying means removing the plug, taking out the existing lower pins, and replacing them with a different set of heights that correspond to a new key. Everything else stays: the housing, the bolt, the strike, the finish, the screws, the hole in your door. From the outside nothing has changed. From the inside, the lock now answers to a different key and to no other, and every key ever cut for it is scrap metal.
That is why the security outcome is identical to new hardware. There is no residual capability in an old key after a rekey, it does not partially work, it does not work with jiggling, it lifts the pins to heights that no longer mean anything.
What rekeying cannot do is change the lock's inherent strength. If the cylinder is a Grade 3 builder-grade unit with a short bolt throw and a thin strike, it is exactly that afterwards. If it can be defeated by attacking the frame, which is how most residential doors actually fail, rekeying does nothing about that, and neither does a shinier cylinder. Which is why the strike plate conversation matters more than the rekey-or-replace one on a great many houses.
The practical upshot: decide rekey versus replace on the key question, then decide separately whether the hardware and the frame are good enough. Those are two different questions and conflating them is how people end up buying new locks that solve nothing.
Decide it
Find your situation.
| Your situation | Correct answer | Why |
|---|---|---|
| Just bought the house | Rekey | Unknown number of keys in circulation. The hardware is not the issue. |
| Tenant moved out | Rekey | Same reason, and batching several units into one visit makes it far cheaper. |
| Keys lost or stolen | Rekey | Every lock that ring opened, including the garage entry and outbuildings. |
| Ex-partner or former housemate has a set | Rekey | Not about trust. About the fact that you cannot compel a return or know about copies. |
| Builders, cleaners or an agent had access | Rekey | Copies accumulate across a project without anyone intending it. |
| Lock is gritty, loose or unreliable | Replace | Rekeying gives you a new key on a lock that is already failing. |
| Front door has only a knob lock | Replace, add a deadbolt | A knob lock is a spring latch with a keyway. It was never meant to be the only lock. |
| Somebody forced or drilled the lock | Replace | Damaged hardware cannot be made reliable again by repinning it. |
| You want a keypad or smart lock | Replace | Different function, not a different key. |
| Key sticks, door needs a shove | Often neither | Usually a worn key or a misaligned strike. Check before buying anything. |
Before you call
Five minutes that change the quote.
- Walk the property and count exterior doors. Front, back, side, kitchen, garage entry, cellar, shed, gate. Owners routinely say two and we find four, and the fourth one found later means a second call-out.
- Check whether your keys already match. If one key opens the front and back, those cylinders share a keyway and keying the rest alike is straightforward.
- Pull one strike plate and look at the screws. Three-quarters of an inch means they are biting into trim and nothing else. That is worth fixing on the same visit whatever else you decide.
- Try the doors for binding. If one needs lifting or shouldering, say so when you call, that is a different fault and it changes what gets brought.
- Decide whether you want one key or several. One key for everything is more convenient. Separate keys for the house and an outbuilding is sometimes deliberate. Say which you want.
- Batch everything into one appointment. Travel and set-up happen once. Every lock after the first costs substantially less on the same visit than on a different day.
Cost
What separates a cheap job from an expensive one.
| Factor | Effect |
|---|---|
| Rekey or replace | The largest single difference. Rekeying reuses hardware you have already paid for; replacement buys it again. |
| Number of cylinders in one visit | Steep savings after the first. This is the factor most in your control and the one people plan for least. |
| Whether cylinders share a keyway | Keying alike is simple when they match and needs a swap when they do not. |
| Grade and type of hardware | Standard residential, mortise, multipoint and high-security are four different jobs. High-security rekeys may need restricted parts and proof of entitlement. |
| Condition of what is fitted | A clean, serviceable cylinder rekeys quickly. A seized or damaged one has to be dealt with first. |
| The hour | Booked daytime work costs less than an emergency call-out. Most rekeys are not emergencies, the exception is when somebody may hold your keys right now. |
| Strikes done at the same time | Adds very little to an existing visit and a lot as a separate one. |
The quote that should make you ask a question
If somebody looks at a house of working locks after a move and quotes replacement across the board without mentioning rekeying as an option, ask directly why rekeying will not do. There are real answers, damaged cylinders, an obsolete keyway, hardware genuinely past service. There is also an answer where new hardware is simply the larger sale.
You are entitled to hear which one applies to your door, in specific terms, before you decide.
Delaware specifics
Which answer is usually right, by housing type.
Wilmington row homes, Elsmere twins, New Castle's historic district. Frequently mortise locks, the heavy rectangular case set into the edge of the door rather than bored through the face. These are almost always a rekey or a rebuild rather than a replacement, because replacing one means new door prep on a door that may be a century old or more. Mortise locks were built to be serviced, and one that has run for eighty years will often run another twenty once cleaned and re-pinned. Most companies quote a replacement because they do not carry mortise parts.
Brookside, Wilmington Manor, Bear and the post-war subdivisions. Here the honest answer is often replace, but not for the reason people expect. The cylinders can be rekeyed perfectly well; the problem is that a lot of these houses have a knob lock doing the primary work with no deadbolt at all. Rekeying that is rekeying a spring latch. The upgrade is the point, not the pinning.
Middletown, Townsend, Cheswold and the new builds. Rekey, and do it in the first week. Builders commonly key a construction phase alike so trades can move between houses, intending to reset each at closing. That step gets skipped more often than anyone admits. Ask a neighbour on your phase to try their front door key in yours, it costs nothing and it answers the question definitively.
Hockessin and Greenville. Often high-security cylinders and multipoint mechanisms, where rekeying is possible but involves restricted components and proof of entitlement. That is the system working as designed rather than an obstacle, and it takes longer for exactly the reason you paid for it.
The short version, if you read nothing else
Rekey when the question is who holds a key. Replace when the hardware itself has failed, or when you want a grade it does not have. Almost every expensive mistake in this area comes from answering the first question with the second answer.
Related
The neighbouring decisions.
If this is a move rather than a security worry, the new-home guide is the one you want. If keys have gone missing, start with lost house keys. And the frame guide covers the part that matters more than either.
Lock Rekeying
Same hardware, new key, every old key dead.
UpgradeLock Replacement
New hardware where the old is worn, damaged or not up to the door.
SecurityDeadbolt Installation
With a reinforced strike and three-inch screws into the framing.
RepairLock Repair
Where the fault is alignment or wear rather than the cylinder.
ElectronicSmart Lock Installation
Retrofit or full replacement, door thickness, and keeping a mechanical override.
All home workResidential Locksmith
The full picture on locks at home across both counties.
Where we do this
Rekeys and replacements across both counties.
Questions
About rekeying and replacing.
Is rekeying less secure than fitting new locks?
No. After a rekey, every key ever cut for that lock is dead and only your new key works. That is the same security outcome as new hardware. What rekeying does not do is upgrade a lock that was weak to begin with, if you had a builder-grade cylinder before, you have a builder-grade cylinder after. Security comes from the grade of the hardware and the strength of the frame, not from whether the metal on the door is new.
How long does a rekey take?
A standard residential cylinder is usually a matter of minutes once the technician is at the door. Most of the time on a rekey visit is travel, walking the property to find every exterior door, and testing at the end. That is exactly why doing all your locks in one visit costs so much less per lock than doing them one at a time.
Can any lock be rekeyed?
Most can, but not all. The cylinder has to be in serviceable condition, the right pinning kit has to exist for that keyway, and some very cheap hardware is effectively sealed. High-security cylinders can be rekeyed but usually need the manufacturer's restricted components and proof you are entitled to them. If yours cannot be rekeyed, we will tell you why rather than just quoting a replacement.
I want all my doors on one key. Is that rekeying?
Yes, it is called keying alike, and it is a rekey where every cylinder gets the same new pinning. The requirement is that the cylinders share a keyway. Where one does not match, we can usually change that single cylinder rather than replacing everything. It is worth doing: people actually lock the side door and the garage entry when the right key is not a nuisance to find.
My locks are forty years old. Rekey or replace?
Look at how they feel rather than how they look. Hardware that still operates smoothly and is decent quality can be rekeyed and go on for years, plenty of old brass is better made than what replaces it. Hardware that is gritty, loose in the door, or was cheap when new has reached the end. Rekeying a worn cylinder buys you a new key on an unreliable lock, which is the worst of both.
Do I need to replace to get a smart lock or a keypad?
Yes, because you are changing the function of the lock, not just the key it accepts. That is a legitimate replacement. Before you buy, check the door thickness and the backset, and keep a mechanical key override where the hardware offers one. And fix the strike first, a smart lock on a door with a thin strike plate is a convenient lock on a weak door.
The locksmith said my lock 'can't be rekeyed' and quoted new hardware. Is that true?
Sometimes it is genuinely true and sometimes it is the easier sale. Ask which specific thing prevents it: the cylinder is damaged, no pinning kit exists for that keyway, or it is a sealed unit. Those are real answers and easy to give when they are true. A vague answer on hardware that operates smoothly is worth a second opinion.
What about the strike plate, does that get changed either way?
It should, and it usually is not. Whether you rekey or replace, the strike plate is the part that decides whether the door resists force, and on most Delaware housing it is a thin plate held by three-quarter-inch screws into door trim. Ask for a reinforced strike with three-inch screws into the framing while the technician is already there. It costs very little added to an existing visit and it is the single highest-value change on the door.
The technician's checklist for deciding
Deciding between rekeying and replacing comes down to a handful of observations that a technician makes in a few minutes. First, is the lock body in good mechanical condition? A cylinder that turns smoothly, a bolt that throws fully and a latch that retracts cleanly are all signs the hardware is sound and rekeying is a sensible choice. Second, is the lock compatible with the keying work required? Some brands are straightforward to rekey, while a few budget models are not designed to be rekeyed at all. Third, does the existing lock meet your needs, or do you want something different, such as a keypad or a higher-grade deadbolt?
Cosmetic and functional condition matter too. A finish that has worn through to bare metal, a handle that wobbles or a thumb turn that sticks is an argument for replacement even if the keys still work, because you will be living with that hardware every day. Conversely, a handsome old lock set that matches the character of the house may be worth keeping and rekeying, provided the internals still work. The technician describes what each choice involves, and the scope and any quote are explained before work begins, so you can choose with the full picture and without pressure.
Finally, consider the reason for the change. If you are responding to lost keys, a move or a former tenant, the goal is to make old keys stop working, and rekeying achieves that. If you are responding to a break-in or a forced entry, damaged hardware and a weak frame may need attention beyond the cylinder. If you want smart features or a different look, replacement is the natural route. Tell us which situation you are in when you call, and we confirm availability for your address in New Castle or Kent County.
How the work differs on the day
A rekey is quiet and quick compared with many people's expectations. The technician removes the cylinder from the door, opens it, swaps the internal pins for a new set matching a new key, and refits it. The door itself is not touched beyond removing a few screws, and the lock continues to look exactly the same. You receive new keys, and the old ones no longer open the lock. Because the hardware stays in place, there is usually no repainting or patching, which makes it a gentle choice for doors with delicate finishes or decorative plates.
Replacement is more involved. The technician removes the old lock, checks the bored holes in the door against the new hardware, and fits the new lock, strike and any new screws. If the existing holes are a different size, adjustments may be needed, and on older doors this can mean filling or enlarging a hole carefully. A new lock should sit square and operate smoothly without forcing. The technician tests it with the door open and closed and checks that the bolt enters the strike fully, because alignment determines whether the new lock actually works well in everyday use.
Either way, a few preparations help. Clear the space around the door, collect the keys you have and decide how many new keys you want cut. Mention any smart devices that connect to the lock, since some hardware pairs with an app or hub. After the work, test every key at least several times and keep one spare somewhere secure outside the house. Ask what the technician noticed about the door, frame or other locks, because the visit is a good chance to hear small concerns before they become larger. We explain the scope and any quote first.