Nearly every smart lock review is written for someone who owns the door. That is why they lead with finish options and deadbolt grades and treat installation as a thirty-minute job with a screwdriver. For a renter, the first question is not how good the lock is. It is whether anything permanent changes — and that single question splits the entire category in two.
Retrofit versus replacement is the whole decision
A retrofitlock does not replace anything. It clamps over the interior side of your existing deadbolt and turns the thumb-turn for you with a motor. The exterior cylinder is untouched, your keys keep working, the landlord's hardware is exactly where they left it, and removal is a few screws and a backing plate. The SwitchBot and August picks on this page are both retrofits, and for most renters one of them is the right buy with no further thought.
A replacementlock takes the old deadbolt out and puts a new one in. You get a slimmer look, often better ecosystem support, and usually a keypad built into the exterior escutcheon — but you have removed your landlord's property, which is a lease question. The Level Lock+ is the most renter-sympathetic replacement because its mechanism hides inside the door, and the eufy C220 is the cheapest. Either way, keep the original lock, its screws and its keys in a labeled box for the day you move out, and photograph the door before you start. Our install guide walks the actual process for both types.
Check your lease, then ask anyway
Most residential leases have a clause about altering locks, and most of the time it exists to make sure the landlord or building keeps access, not to stop you adding convenience. A retrofit lock sidesteps the clause entirely, because nothing about the lock they can see or key has changed — which is a genuinely useful thing to be able to say. For a replacement, the conversation that usually works is simple: you will install it yourself, you will keep the original hardware, you will reinstall it at move-out, and the landlord gets a key or a code for the new one. Plenty of landlords say yes to that. Almost none say yes to discovering a new lock at inspection.
Your real problem is probably access sharing, not security
Renters buy smart locks for a specific set of reasons, and "the deadbolt is not strong enough" is rarely one of them. It is roommates who lose keys. It is a partner who needs access two nights a week. It is a dog walker, a cleaner, a friend collecting a parcel, a building super. Copying keys for all of those is expensive, slow and irreversible — a code or a fingerprint is instant and revocable. That is why both retrofit picks here include a keypad, and it is the feature to prioritize over almost everything else. If you are hosting rather than living there, best smart locks for Airbnb covers the short-let version of the same problem, which has different requirements.
Buy a lock that survives the move
You will take this lock to at least one more apartment, so judge it on three things beyond the spec sheet. Does it come off cleanly — retrofits win outright. Does it work on a different door — a retrofit works on any standard deadbolt, a replacement has to match the new door's backset and thickness. And does it re-pair to a new Wi-Fi network without a support ticket — all four here do, but it is worth checking the app before you pack. This is also the argument against buying a lock whose features depend on a hub you may not keep: the SwitchBot combo includes its hub, which is the right shape; a lock needing a bridge you buy separately is one more thing to carry. Our do smart locks need a hub guide explains which designs depend on one and why.
What about the ecosystem question?
Only one lock here reaches Matter — the SwitchBot combo, via its included Hub Mini — and that is a meaningful advantage if you intend to keep adding devices, because Matter is the one standard that will still mean something in your next apartment regardless of which assistant you end up on. Level is the Apple answer with HomeKit and Apple Home Key but no Matter. August and eufy are Alexa and Google. If you have not settled on an ecosystem yet, our lock compatibility guide maps the whole field, and the main smart lock roundup ranks the category without the rental constraint. For the two retrofit-versus-replacement comparisons most renters end up reading, Level Lock+ vs August is the direct head-to-head, and Aqara U100 vs Level Lock+ covers the Apple-focused alternative.
Measure the inside of your door before you order a retrofit
A retrofit lock has exactly one hard requirement: physical room to mount over the interior thumb-turn. Three things eat that room — deep interior trim or molding around the frame, a thumb-turn set unusually close to the edge of the door, and anything that swings across the door such as a storm door or a closet. Hold your phone where the lock body would sit and open the door fully. If it clears, you are fine. This is the single most common reason a retrofit lock gets returned, and it takes ninety seconds to check.
Fix a sticky deadbolt first, or do not buy a motor
A retrofit lock turns your existing bolt with a small motor. If you currently have to lift, push or lean on the door to throw the deadbolt, that lock will struggle, drain its batteries and eventually report a jam. The fix is usually a misaligned strike plate, which is a maintenance request your landlord should want to know about anyway, and it is worth sorting before the lock arrives rather than blaming the lock afterward. The same goes for a replacement: a new deadbolt in a door whose frame has dropped will have the same problem.
Keep a physical way in, and know what it is
On both retrofits here, the answer is comfortable: your original key still works, because the original cylinder is still there. On the eufy C220, a keyed cylinder is part of the lock. On the Level Lock+, you get Level's own keys — so put one somewhere that is not inside the apartment. The failure mode to plan for is not a hack; it is a flat battery on a day you were not paying attention, and the honest version of that discussion is in do smart locks work without power and can you use a key with a smart lock.
Then think about what else the lock should trigger
The reason to care about Matter or ecosystem support on a rental lock is not voice control, it is routines: the door locking when you leave, a lamp coming on when a code is used at night, a notification when the dog walker arrives. That is where the SwitchBot combo's included hub earns its price, and it is the one upgrade path that will still work in your next apartment. If a lock is the first smart device you are buying, best smart home devices for renters covers what to add next, and best smart padlocks handles the storage unit, bike or basement cage that a deadbolt cannot.
