Choose a smart lock: door fit, connection path and access methods

Measure the door before reading features

Three numbers decide whether a full-replacement deadbolt will go on without new holes: the backset from the door edge to the centre of the bore, the door thickness, and the bore diameters. US locks in this catalogue document backsets of 2-3/8 in or 2-3/4 in, a 1 in edge bore and a 1-1/2 in or 2-1/8 in cross bore. Door thickness limits are where the products differ. Schlage states 1-3/8 in to 1-3/4 in for the standard Encode Plus and sells a thick-door kit separately for 1-7/8 in to 2-1/2 in doors; Yale states 1-3/8 in to 2-1/4 in for the Assure Lock 2 Touch; Aqara states 35 to 55 mm for the U100 and eufy 35 to 55 mm for the E330.

Treat a phrase like fits most doors as a reason to keep looking. When a manufacturer publishes no thickness range at all, as the Aqara U400 pages and manual do at the time of checking, ask support for your door before ordering. A retrofit lock that mounts over the existing interior thumbturn keeps your current bolt and keyway, so its fit question is about the existing cylinder rather than the bore; the U400, U100, E330, Encode Plus and Assure Lock 2 Touch recorded here are all full-replacement or deadbolt-prep designs that supply their own bolt.

Decide how the lock will connect

Write down the path from the lock to your phone, because each path needs different equipment. Built-in Wi-Fi reaches the maker's app without extra hardware; Schlage and Yale document a 2.4 GHz network requirement, while the retrieved eufy E330 page does not state the required Wi-Fi band. For Matter ecosystem use, Aqara documents a Thread-enabled Matter controller for the U400, sold separately. A Zigbee lock such as the Aqara U100 needs the maker's hub for remote unlock, automations and any Matter exposure. Z-Wave versions exist in some families and need a Z-Wave controller.

Keep the claims apart. Matter is an application layer, Thread is a wireless networking protocol, Apple Home Key is a wallet credential, and UWB hands-free unlocking is a further feature with its own hub and phone requirements. A manufacturer can document one without the others, and a label on a family comparison page is not a statement about the SKU in your basket; the Encode Plus records here leave Matter and Thread unresolved for exactly that reason. Published support is also not a tested interoperability or security result, and every ecosystem may expose a different subset of lock features.

List the access methods for the exact SKU

Count the ways a person can open the door: keypad or touchscreen codes, a fingerprint reader, a phone app, Apple Home Key, and a mechanical key. The same family often sells keyed and key-free versions, or a Touch model with a fingerprint reader and a Plus model with Home Key, under one product page. Yale's own comparison grid assigns Home Key to its Plus model only, while the Touch adds the fingerprint reader. Schlage's Encode Plus documents codes, Home Key, app and key, with no fingerprint reader. Aqara's U400 and U100 document fingerprint, codes, NFC, Home Key and keys, and eufy's E330 documents fingerprint, codes, app and keys but states no Apple HomeKit support.

Stated fingerprint accuracy percentages, code capacities and months of battery life are manufacturer figures under their own assumptions. Record them as claims, and plan a backup: a physical key you actually keep somewhere, or the emergency USB-C power port that several of these locks document on the outer panel.

Choose a power routine

Replaceable cells and rechargeable packs ask for different habits. The Encode Plus, Assure Lock 2 Touch and U100 run on four AA batteries that you swap when the low-battery warning appears. The U400 uses a 7.3 V rechargeable lithium-ion pack charged through USB-C on the inner panel or removed and charged separately; the E330 has a built-in 10,000 mAh pack, and eufy states that its outer port supplies emergency power only and cannot charge the battery. A lock with a camera and doorbell, like the E330, powers those features from the same battery, so its stated life is not comparable with a keypad-only lock.

Confirm the package, not the family

Match the seller's model code to the manufacturer's specification before you pay. Trim names and finish codes change the SKU, and handleset bundles, hub bundles, chime bundles and kits with NFC cards are different offers. A controller, hub, bridge or thick-door kit that a feature depends on is included only when the package list says so; the Aqara U400 DL-D06E and U100 Gray packages recorded here contain no hub, and eufy's E330 ships without a chime or HomeBase. Where a seller and a manufacturer publish different model suffixes or a store page does not label a kit, keep that doubt visible and resolve it with the seller.

Grades such as ANSI/BHMA Grade 2, Grade 3 or AAA appear in this catalogue only as the manufacturer states them for the lock. They describe laboratory classifications of the product, not your strike plate, frame or installation, and this guide does not give installation or security advice beyond following the manufacturer's requirements for your door.