How to choose a smart door lock
Check the door before the lock
Most locks here replace a US single-cylinder deadbolt; European doors use a Euro cylinder and need a lock made for it. The Installation row tells you whether a lock is a full replacement, with its own keyway, or a retrofit that goes over the inside thumb-turn and keeps your existing keys — the easier option for renters. Measure the door thickness and the backset (centre of the hole to the door edge) before you order.
Security grades, in plain words
ANSI/BHMA grades the mechanical lock: Grade 1 is the strongest, Grade 3 is the residential minimum, and the newer A156.40 standard rates residential locks from C to AAA across security, durability and finish. A certified grade is worth more than a maker’s “meets the standard” statement, and we label the two differently in the Security certification row. None of this covers the electronics, which is where unique codes and auto-lock come in.
Ways in
A keypad is the one everyone in the house can use. Fingerprint readers are quicker but struggle with wet or cold fingers. NFC and Apple Home Key let you tap a phone or watch on the lock; Home Key only works with Apple devices and an Apple Home setup. Auto-unlock, which opens the door as your phone approaches, is convenient and the feature most likely to misfire, so look for a lock that pairs it with a door sensor.
Radios, hubs and battery life
Wi-Fi locks reach your phone from anywhere without a hub, and pay for it in battery life. Thread locks sip power and pair through Matter, but need a border router. Zigbee locks need a hub; Bluetooth-only locks need your phone nearby. The battery life we list is the maker’s own estimate under its own assumptions — treat it as a comparison between locks rather than a promise — and note whether it runs on AA cells you can buy anywhere or a rechargeable pack you have to remember to charge.
Matter, Home Key and what stays in the app
Matter gives Apple Home, Google Home, Alexa and Home Assistant local lock, unlock and status, and on recent platforms the PIN codes too. Enrolling fingerprints, setting auto-lock timers and firmware updates still happen in the brand’s own app, and that app may want an account. The Privacy rows show whether the lock needs a cloud account and whether any feature sits behind a subscription.