You will touch this lock every day for years. A poor fit or a missing feature stays with you; it does not wear off with time. Most of the regret is predictable, and it usually comes from buying on specs and brand instead of on the door in front of you and the people moving through it. The decisions below settle whether the lock works out.
Start with the door, not the lock
Before you look at a single product, measure the door. Fitting comes before features — a lock that does not fit the bore or the hand is going back in the box, however good its app is. The three numbers that matter:
- Door thickness. Most residential locks fit doors 35–55 mm. Thicker doors (some security doors, double-skin metal doors) need an extension spindle or kit.
- Backset. The distance from the door edge to the centre of the bore — typically 60 mm or 70 mm. The wrong backset means the latch cannot reach the strike.
- Cross-bore and latch bore. The cross-bore (the large hole through the face) is usually 38–54 mm; the latch bore (the edge hole) about 25 mm. Non-standard bores mean drilling.
Also note the door's hand (left/right, inswing/outswing) and whether it carries a separate handle, because some smart locks replace only the deadbolt while others are full-handle mortise units.
Choose your credentials
The credential is what you live with day to day. Pick for the people who use the door, not for the spec sheet.
| Credential | Best for | Trade-off |
|---|---|---|
| Fingerprint | Daily family use | Fast, but a wet or cut finger can fail; awkward for many guests |
| Passcode | Guests, kids, backup | Universal, but slower and visible to onlookers |
| IC card | Elderly users, offices | Tap-and-go, but a physical object to lose |
| App / Bluetooth | Owners, remote users | Richest features, but useless if the phone is dead |
For a family home, a lock that covers all four bases is usually the right one: fingerprint for the daily flow, a passcode for guests, a card for anyone who struggles with a reader, and the app for management. The underlying mechanics — how each credential is checked on the device — are covered in how smart locks work.
Decide on connectivity
This is the decision that confuses buyers most. A Bluetooth-only lock is not a cut-down Wi-Fi lock; the two are built for different situations.
- Bluetooth (BLE) direct. The lock talks to your phone when you are nearby. No extra hardware, long battery life, and it works when the internet is down. The catch: no remote control when you are away from home.
- Add a gateway. A small bridge device links the lock to your home network and the cloud. That unlocks remote control, real-time alerts, and time-limited codes for guests or cleaners.
A simple way to decide: if you only ever open the door while standing in front of it, BLE is enough. The moment you want to let someone in from work, or see who came and went, add a gateway. The full trade-off is set out in our protocol comparison.
Power: batteries or wired
Most home locks run on AA batteries for 8–12 months, with low-voltage warnings that start weeks before the lock actually dies. That is plenty for a home — and a flat battery should never lock you out, because a good lock keeps a mechanical key override or an emergency USB port.
Wired power is worth it only for very high-traffic doors or where changing batteries is awkward (a shared gate, for example). For a single home entry, batteries are the pragmatic choice.
Security fundamentals
A few non-negotiables, regardless of brand:
- Local authorisation. The lock verifies credentials on the device, not by phoning home. Otherwise the door fails — or worse, opens — when the internet is down.
- Encrypted communication. App-to-lock and gateway-to-lock traffic must be encrypted, so a captured signal cannot be replayed.
- Revocable permissions. A lost phone or a leaked passcode must be revocable in seconds from the app.
- A real mechanical backup. A key override or external emergency port, so no software fault can trap you inside or outside.
Match features to budget
Smart locks span roughly three tiers; the value lies in matching the tier to the door:
- Entry tier. Fingerprint, passcode and card, Bluetooth-only — right for a side door or low-traffic rental.
- Mid tier. Adds a gateway, remote control and time-limited codes — the usual fit for a primary home entry.
- Premium tier. Mortise construction, anti-pry sensors, a camera and deeper integration — for a main entrance where security and finish both matter.
Avoid paying for features you will not use: a camera-equipped Wi-Fi lock on a low-traffic laundry door is money spent for nothing.
Where buyers tend to go wrong
- Buying on app features, ignoring build quality. Security sits in the motor, bolt and anti-pry design — the app is just convenience, even though it is what sells. Get that backwards and the lock disappoints within a year.
- Assuming "Wi-Fi" means "better." It often means shorter battery life and a dependence on your router staying up.
- Forgetting the door's hand or handle. A lock that fits the bore but fights the handle turns into a daily annoyance.
- Skipping the mechanical backup. Software alone should not be the only thing standing between you and your door.
Work through the door first — thickness, backset, bore, hand — then pick credentials for the people who use it, decide whether remote matters enough to add a gateway, and do not trade build quality for a longer feature list. Follow that order and the lock tends to disappear into daily life. The Sciener smart lock range shows those principles applied across the three tiers.