The smart lock guide: start with your door

Almost every smart lock question turns out to be a door question. Not “which brand is best”, but “what is already fitted to this door, and what will physically go where it is”. Answer that and the shortlist gets very short very quickly.

This page is the map. Work down the four questions, and each one sends you to the guide that covers your case. If you would rather browse, the five sections are Installation, Compatibility, Renters, Troubleshooting and Buying.

Question one: are you allowed to change the door?

Start here, because it removes most of the catalogue before you have spent anything. If you do not own the door, or the lease says the original hardware has to go back on when you leave, you are looking for something that comes off without a trace.

The usual answer is a retrofit unit that replaces only the interior thumbturn. Our guide for renters covers what comes off cleanly and what will cost you the deposit, and what your lease actually decides goes through the permission question properly. If drilling is out entirely, there are ways to add a second lock without making a hole.

Letting the place out is a different job again, with its own requirements around guest codes and turnover: start with what a short-term rental lock needs and, if you are still deciding, lockbox versus keypad. Letting a cleaner, dog walker or contractor in on a schedule is covered in temporary access codes, and if you own a condo or townhouse, check what your HOA can require before you change the front door.

Question two: what is on the door right now?

Open the door and look at the edge. What you find decides which of three installation types you are in.

• A round deadbolt above a handle. The easy case, and the one most products are built for. The full walkthrough is in smart lock installation, and removing the old deadbolt covers the part that actually goes wrong.
• A deadbolt you want to keep. Then you want a retrofit, and the question is whether one will clamp onto what you have. The fit check is four measurements.
• A knob and nothing else. Common on garage-to-house and back doors. Your options with no deadbolt covers both fitting one and working around it, and adding a bore is the carpentry route.
• A long plate down the edge of the door. That is a mortise lock, and the list of smart locks that fit one is short. Which ones actually fit.
• A sliding patio door. A category of its own, with its own hardware. What fits a slider.

If the answer is “I am not sure it is worth doing myself”, the cost comparison lays out where a locksmith stops being an admission of defeat.

Question three: what has to be able to see the lock?

This is where most disappointment comes from. A lock can be perfectly fitted and still refuse to appear in the app you expected, because the radio inside it is not the one your house speaks.

Start with Bluetooth, Wi-Fi or a hub, which explains what each connection can and cannot do from outside the house. Then check your own platform: Google Home, Apple Home, or Alexa, each of which has a rule about unlocking by voice that people find out about late.

If the box says Matter, read what the badge actually guarantees before assuming it solves compatibility, and if it says Matter over Thread you will also need a border router. Older Z-Wave models still need a hub, and no phone has ever had the radio for them.

Question four: how do you want to open it?

Only now does the product category matter. The five types of keyless entry lock separates a forty dollar mechanical pushbutton from a connected deadbolt, and keypad, fingerprint, app or card compares them by how each one fails rather than by how each one is advertised.

Three more decisions sit alongside that one: deadbolt, lever or handleset for the body shape, single or double cylinder where a glass panel is involved and local code has an opinion, and what an ANSI grade buys you when two locks look identical and are priced fifty dollars apart.

Two questions come up constantly and both have unglamorous answers: whether a smart lock can be hacked, and what a lock on an exposed door has to survive.

When it is already fitted and misbehaving

Most faults are mechanical, not electronic, and the lock usually told you before it stopped. If the bolt is stalling or grinding, that is alignment and binding nine times out of ten. If the lock is dying every few weeks, the batteries guide covers which cells these locks actually want.

For the rest: a keypad that will not respond, a lock that will not join Wi-Fi, beeps and flashing lights, and resetting and re-pairing without losing your codes. If the door is found unlocked when nobody touched it, a lock that unlocks on its own walks through the settings and automations that usually explain it.

The short version

Check whether you are allowed to change the door, then measure what is already on it, then confirm the lock speaks the same language as your house, and only then pick how you want to open it. Doing those in the other order is how people end up returning a lock that was never going to fit.

How these guides are researched, and what we deliberately do not claim, is set out in our editorial standards.