How to Choose a Smart Lock | Fit First, Then Features

Choosing a smart lock starts with measuring your door, not comparing features.

Most smart lock returns happen because someone bought a lock before checking their door’s measurements and existing hardware. The right way to choose a smart lock is to verify your door’s geometry first, then match the lock’s power source, app support, and access features to your actual use case. Get the fit right and the rest falls into place; get it wrong and you’ll be sending it back.

What Door Measurements Matter Most

Four measurements decide whether a lock physically fits your door: door thickness, backset, cross-bore diameter, and the existing lock type. These are the standard fit gates in smart lock compatibility guides, and skipping them is the most common buying mistake.

• Door thickness — standard US interior and exterior doors run about 1¾ inches, but some specialty doors are thicker or thinner.
• Backset — the distance from the door edge to the center of the deadbolt hole, typically 2⅜ or 2¾ inches.
• Cross bore — the diameter of the large hole drilled through the door, usually 2⅛ inches.
• Lock type — is it a standard deadbolt, a mortise lock, or a multipoint system?

Some locks have tighter requirements. Yale’s Conexis L1, for instance, requires a door thickness of 44–70 mm plus a specific 92 mm centre measurement from cylinder to handle, and it won’t work with Avantis multipoint door locks at all. If your door uses a multipoint system, confirm the smart lock you’re considering supports that format before buying.

Power and App Compatibility: Check These Before You Buy

Smart locks are software products as much as hardware, and app compatibility can block setup even when the lock physically fits. Check your phone’s operating system against the lock’s requirements, plus how the lock connects and what accessories it needs.

• Phone OS minimums — eufy Security’s Smart Lock Wi-Fi works with the eufy Security app on iOS 10.2 or later and Android 5.0 or later.
• Power source — many deadbolt-style locks run on 4 AA batteries, and batteries may not be included in the box.
• Hub and bridge needs — some ecosystems require an extra hub or bridge before the lock will work with Alexa, Google Home, or Apple Home.
• Wi-Fi band — if the lock needs Wi-Fi, confirm it works on 2.4 GHz networks, since many routers route IoT devices that way.
• App choice — Tuya-based locks typically need the Tuya Smart or Smart Life app plus Bluetooth during pairing.

If you already live inside one smart-home ecosystem, make sure the lock you choose integrates with it — but only after you’ve verified the physical fit. Integration doesn’t matter if the lock won’t mount.

How to Install and Set Up a Smart Lock

Setup usually follows the same pattern regardless of brand: install the hardware, then pair the lock through the manufacturer’s app. Most apps guide you through both stages on screen.

1. Install the deadbolt or latch — align the included template on your door, drill holes to the specified backset and height, and install the deadbolt so the knob or latch sits in the correct orientation. Manuals require manual testing before powering on.
2. Mount the units — attach the exterior and interior pieces to the door, keeping the supplied screws organized.
3. Install the app — download the manufacturer’s app, create or sign in to an account, and enable phone Bluetooth.
4. Pair the lock — follow the in-app prompts. For eufy Wi-Fi locks, scan the QR code on the back of the device to pull up Bluetooth information and finish pairing.
5. Test everything — lock and unlock from both the keypad and the app before you rely on it.

The most common failure point is pairing: if the app can’t find the lock, check that Bluetooth is on, the lock has fresh batteries, and you’re standing within range. On Tuya-style locks, the add-device screen is where you’ll start that process.

Your Smart Lock Buying Checklist

Work through this list in order, and you’ll avoid the mistakes that send most locks back.

• Measure door thickness, backset, and cross-bore diameter.
• Confirm your lock type: standard deadbolt, multipoint, or another system.
• Check app support for your phone’s OS version.
• Verify the power source and whether batteries are included.
• Confirm hub or subscription requirements for your smart-home ecosystem.
• Check Wi-Fi band support if the lock needs network access.

If you’ve measured and checked compatibility, you’re ready to compare specific models. Our tested roundup of the best automatic door locks can help you compare top options side by side.