Product Library / Smart Locks

Aqara Smart Lock U400

Compiled by SmartHomeWorkflow Research · Aqara · Smart Locks · ~$269.99 (at time of research — $269.99 read from Aqara's own storefront structured data (SKUs DTC-US-EN-U400-BLACK and DTC-US-EN-U400-SLIVER, both in stock at the same price) rather than the rendered page, per this vendor's standing method rule. ⚠ Budget beyond the lock if UWB hands-free unlocking is why you want it: Aqara requires 'a Thread-enabled Apple Home hub' for that feature, which is a HomePod or Apple TV you may not already own. Never treated as a live price.)

⚠ Similar names, different products: A different ARCHITECTURE from the Aqara Smart Lock U200 (aqara-smart-lock-u200) already in this catalogue, not just a higher number: the U200 is a retrofit that mounts over your existing deadbolt from the inside, while the U400 replaces the whole lock — it has its own rekeyable cylinder and physical key. That decides whether you keep your current keys, and it puts the two products in different subcategories on this site.

Compatibility

? Inconclusive means we researched that ecosystem and the evidence doesn’t settle it — the catch says why, and the sources are listed below. It is a statement about the available evidence, never a verdict on the product. A Setup Check researches your exact setup where the official sources don’t answer.

Protocols: THREAD · MATTER · BLUETOOTH · NFC^[1][5]

Needs before it works: Not for the lock's basic operation — fingerprint, passcode, NFC card and physical key all work at the door with nothing else in the house. But two of the features Aqara sells it on DO require hardware you buy separately, and Aqara names them precisely: UWB hands-free unlocking needs 'a Thread-enabled Apple Home hub', and tap-to-unlock needs 'an Apple Thread-enabled Matter controller'. In practice that means a HomePod, a HomePod mini or a Thread-capable Apple TV 4K; the Wi-Fi-only Apple TV 4K has no Thread radio and does not qualify. Anything Thread-based also needs a Thread border router to reach your phone remotely, which is the same box. If the hands-free trick is the reason you are buying this lock, price that hub alongside it.^[1]

What it can do^[4]

Listed capabilities are what we could establish from vendor documentation. An ability missing here is unestablished — not necessarily absent.

Subscription reality^[1]

✓ Works without a subscription: Yes.

Vendor account required: Optional — there is a documented way to use it without one.^[6]

No plan, tier or recurring fee is named anywhere in Aqara's own product content for this lock — access methods, the app and the Matter integration are the product rather than a subscription level of it. That is the norm for locks in this catalogue and worth stating explicitly, since it is not the norm for the camera shelf next door. ⚠ One adjacent cost that is not a lock subscription but will feel like one: the video-unlock feature works by integrating with Aqara cameras, which have their own storage economics.

Maintenance reality

• Batteries: removable rechargeable lithium — expect roughly 6 months per set
• Works without the internet: Not established — we have not sourced this yet. It does not mean the product fails without the internet.
• A removable rechargeable lithium pack rated 'up to 6 months per charge', and Aqara solves the annoyance that usually comes with that: the lock can be recharged over USB-C 'without disconnecting the lock', so you are not taking the door apart twice a year. Built for an exterior door — 'BHMA-certified for mechanical strength' and 'IP65-rated weatherproofing'. And the physical fallback is genuinely physical: the cylinder is rekeyable, so a lost key means recutting rather than replacing the lock.

Security updates^[3]

Aqara publishes no security-update support date for this model. That is a gap in what the manufacturer has published, not evidence either way — some makers declare a support period and some say nothing at all.

VERIFIED ABSENCE, earned by walking all three source rungs on 2026-08-19 rather than defaulted. (a) Aqara's own compliance library at aqara.com/en/security-certifications/ enumerates 59 products WITH their model numbers, and the Smart Lock U400 is not among them — this is an enumerated first-party index, not a search, which is what makes the absence evidence rather than silence. (b) Aqara's 2024-08 Product Security Support Policy table lists neither the product nor its model numbers. (c) The product's own page carries no security-update, end-of-support or patching statement of any kind. So Aqara publishes a support period for much of its range and has published none for this model. ⚠ This has a shelf life: Aqara adds statements to that library over time (the Doorbell Camera Hub G410's is dated May 2025, later than most), and UK PSTI obligations apply to products on sale — so the absence is a fact about today, not a permanent one.

The catch

The feature that sells this lock is not in the box. UWB hands-free unlocking — the door opening as you walk up — needs a Thread-enabled Apple Home hub by Aqara's own words, meaning a HomePod or a Wi-Fi + Ethernet Apple TV 4K bought separately, and tap-to-unlock needs the same thing. Buy it without one and you own a very good fingerprint-and-keypad deadbolt at $269.99. Two more things worth knowing: it replaces your entire lock rather than retrofitting over it, so your existing keys stop working, and Aqara names only Apple Home explicitly — Alexa, Google, SmartThings and Home Assistant are all left unstated on this product's own page even though the lock speaks Matter.

Who it's for

An Apple household that already owns a HomePod or a Thread-capable Apple TV 4K and wants the closest thing to a door that recognises you — UWB hands-free entry is genuinely rare, and this is one of the few locks doing it. It also covers the unglamorous cases: fingerprint, passcode, NFC card and a rekeyable physical key, BHMA-certified and IP65 for a real exterior door. If you want to keep your existing keys and cylinder, the U200 retrofit answers a different question on the same shelf.

Sources & method

Numbered sources below back the facts marked with the matching number above. This is a research profile: compiled from manufacturer documentation, certification registries, and published testing — we state facts, not verdicts, and we have not physically tested this unit. How we work →

1. [1] us.aqara.com, structured storefront endpoint for the Smart Lock U400 — vendor structured-endpoint read (Shopify .js, per the standing method rule for this vendor), verified 2026-08-17
   Backs: Product identity, Price, Protocols, Power source, Installation, Required hub or bridge, Subscription, Batteries, Market availability, Research status, Amazon Alexa compatibility, Google Home compatibility, Apple Home compatibility, SmartThings compatibility, Home Assistant compatibility
2. [2] us.aqara.com structured storefront endpoint for the Smart Lock U400, the only source this record cites — evidence read against sources this record already cites (BQ-187 capabilities population) — no field changed, verified 2026-08-19
3. [3] Three first-party surfaces checked 2026-08-19 and all three silent for this model: Aqara's compliance library at https://www.aqara.com/en/security-certifications/ (enumerates 59 products with model numbers; this one absent), Aqara's Product Security Support Policy at https://www.aqara.com/wp-content/uploads/2024/08/Product-Security-Support-Policy.pdf (table lists neither the product nor its models), and the product's own page at https://www.aqara.com/us/product/smart-lock-u400/ (no security-update, end-of-support or patching statement present). — first-party regulatory declaration read (BQ-192 security-support sweep, method note 69 precedence) — absence recorded as absence, all three rungs walked, verified 2026-08-19
   Backs: Security-update support period
4. [4] https://us.aqara.com/products/smart-lock-u400 — the vendor's own product page (read 2026-08-19) — first-party vendor product page, plain fetch, verified 2026-08-19
   Backs: Capabilities
5. [5] This record's existing per-model Matter evidence, re-read 2026-08-20 against the ruled definition of `protocols`: a transport statement · Matter over Thread. No new external source was fetched — the evidence already on this record was re-examined and this entry states what it establishes. — protocols-definition sweep (BQ-222 batch 2; ruling §1 of docs/decisions/2026-08-20-RULINGS-SITTING.md), verified 2026-08-20
   Backs: Protocols
6. [6] Aqara Smart Lock U400 user manual, 'Instructions before Installation' — "Before using this product, you need to download the Aqara Home app and register an account. This is not necessary if you directly connect this product to a third-party ecosystem, however, unique features such as Night Latch mode, Auto-Lock settings and more will be unavailable to you." — vendor-page research, verified 2026-08-21
   Backs: Vendor account required
7. [7] Apple Support, ‘Set up your HomePod, HomePod mini, or Apple TV as a home hub’, read together with ‘Identify your Apple TV model’ at support.apple.com/en-us/101605. — first-party browser-rendered read (interactive session), verified 2026-09-06

Compatibility and lifecycle information reflects the last-verified date above and can change without notice (firmware updates, cloud-service changes, discontinuations). It is provided as-is, for information — verify with the manufacturer before purchasing. Spot an error? Tell us and we'll fix it. Full terms: Terms of Service.

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