Aqara · Reviewed by Edgar ’s Home Tech · Published 2026-03-15
Based on a review by Edgar ’s Home Tech (accessed 2026-03-15).
Based on this review alone: buy it if you care about reliable ultra-wideband (uwb) auto-unlock based on proximity and direction — just accept keypad brightness is too dim and not adjustable, making the lock icon hard to see at night.
The reviewer concludes that the Aqara U400 is "one of the most complete smart lock that is as future-proof as it gets" thanks to its Matter over Thread, Ultra-Wideband (UWB), and Aliro support. He considers it "probably the best smart lock that I've tested ever," despite a minor criticism regarding keypad brightness.
This review provides an in-depth look at the Aqara U400 smart lock, highlighting its Ultra-Wideband (UWB) auto-unlock capabilities and its compatibility with various smart home ecosystems. The reviewer tests the lock for over 30 days, covering aspects like installation, battery performance, and various unlock methods. The review also touches upon the lock's material quality and price points.
The Aqara U400 is an exceptional smart lock, lauded as potentially the best the reviewer has ever tested, primarily due to its reliable Ultra-Wideband (UWB) auto-unlock. Unlike geofencing, UWB precisely determines proximity and direction, preventing accidental unlocks when merely driving by, and allowing the lock to automatically open just a step away from the door without manual interaction. Its main drawbacks include a dim keypad backlight that is hard to see at night and the absence of a "passage mode" for temporary unlatching. If you desire a future-proof smart lock with seamless, accurate auto-unlocking and broad smart home compatibility, this product is highly recommended. However, if bright keypad visibility for nighttime use is crucial, you might find it slightly inconvenient.
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comparisonpositivet=01:00–01:40
The reviewer explains that UWB differs significantly from older geofencing technology by working based on proximity and direction, preventing accidental unlocks. After a month of testing, the UWB feature worked flawlessly, unlocking the door when the reviewer was a step away, though he sometimes wished it was 'a hair faster'.
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The reviewer states that UWB knows if he is walking feet away from the door and not trying to walk in, and even if he is inside the house next to it, it wouldn't open. This reliability was confirmed, as the lock "never did that," meaning it never accidentally opened when he was inside.
hands_on_demopositivet=02:20–02:45
The reviewer describes being amazed after a month of use that he doesn't need to tap his watch or use his phone; the door is automatically open. He simply turns the handle and walks in, calling it a "new step forward" that truly feels like the future.
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The lock is compatible with Matter over Thread, which means it works with all major ecosystems like Apple Home, Samsung SmartThings, and Google Home. The reviewer notes this is the "most important one to me."
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The Aqara U400 is one of the first locks to support Aliro, a smart lock standard for digital keys created by the Connectivity Standards Alliance. This allows features like Apple Home Key to be universal, meaning Android users can also tap their digital key to unlock.
visual_inspectionmixedt=04:00–04:30
The reviewer notes that the inside part of the smart lock is plastic, but the outside part is more durable and made of metal. He mentions some people complained about the material.
comparisonneutralt=04:50–05:25
The standard lock is priced at $269.99. A deluxe version with an entirely brushed metal build and two batteries costs $299.95.
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The lock supports multiple unlock methods: a keypad for codes, fingerprint access, NFC tags (sold separately), Apple Home Key, a physical key, and Ultra-Wideband (UWB).
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The installation process was "pretty easy, just like any other lock." The reviewer chose to keep his old deadbolt but followed the steps to set up the lock in the app.
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Aqara claims the rechargeable battery can last up to 6 months on a single charge. The reviewer advises charging it first before installation.
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Despite initial skepticism about rechargeable batteries, the reviewer found it cool and easy to charge using a battery bank or USB cable, preferring it over the tedious process of replacing AA batteries in his previous U100.
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The lock can be connected via the Aqara app and paired with a Matter controller like the G410 doorbell. Alternatively, it can be connected directly to an ecosystem using the Matter QR code without the Aqara app.
reviewer_claimnegativet=08:00–08:50
The reviewer was expecting a 'passage mode' feature, which his previous U100 had. This mode would keep the door unlocked for a set period when frequently going in and out, preventing constant locking and unlocking, thus saving battery.
reviewer_claimpositivet=08:50–09:40
Adding the lock to Apple Home provides information like battery level, 'approach direction' (a new UWB-specific option), and managed access for organizing users. The approach direction helps the lock understand the user's incoming direction to trigger UWB.
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A dislike is the keypad brightness; the reviewer wishes it could be adjusted in the app. He finds the lock icon, used for locking when leaving, to be very dark at night, making it hard to see. He believes this could be fixed with a firmware update.
The reviewer found the UWB auto-unlock feature to work flawlessly and reliably over 30 days. Unlike geofencing, it uses proximity and direction, preventing accidental unlocks when merely driving by or being inside the house. The lock unlocks automatically when you are a step away, making entry seamless, although the reviewer sometimes wished it was 'a hair faster'.
The Aqara U400 supports Matter over Thread, which allows it to work with all major smart home ecosystems such as Apple Home, Samsung SmartThings, and Google Home. The reviewer emphasizes its integration into Apple Home, providing battery level and a new 'approach direction' setting. It can be set up directly with a Matter QR code or through the Aqara app.
The Aqara U400 supports Aliro, a smart lock standard for digital keys created by the Connectivity Standards Alliance (the creators of Matter). This technology, working with Matter, ensures that digital keys like Apple Home Key are not exclusive to Apple, meaning Android users will also be able to tap their phones to unlock it.
The reviewer notes that the standard Aqara U400 has a durable metal exterior, but the inside component is plastic. An optional deluxe version, priced higher at $299.95 compared to the standard $269.99, offers an entirely brushed metal build and includes two batteries.
The Aqara U400 comes with a rechargeable battery, a departure from the AA batteries used in the reviewer's previous Aqara U100. While initially skeptical, the reviewer appreciated the convenience of charging it with a battery bank or USB cable, finding it much less tedious than constantly replacing batteries. Aqara claims up to 6 months of battery life on a single charge.
The reviewer points out two missing or subpar features. He missed the 'passage mode' from his previous U100, which allowed the door to remain unlocked for temporary frequent access without wasting battery with constant auto-locking. Additionally, he found the keypad's lock icon and overall brightness to be too dim at night or in dark conditions, making it hard to see and use, suggesting a firmware update could fix this.
The Aqara U400 is packed with various unlock methods to suit different preferences. These include a traditional keypad for codes, a fingerprint sensor for quick biometric access, NFC tags (available separately from Aqara), Apple Home Key functionality, a physical key for manual override, and the advanced Ultra-Wideband (UWB) feature for automatic, proximity-based unlocking.
85/100 source quality
Edgar's Home Tech reviews the Aqara U400 smart lock after 30 days of use, emphasizing its reliable and precise Ultra-Wideband (UWB) auto-unlock feature that distinguishes it from geofencing. The lock supports Matter over Thread for broad ecosystem compatibility and is an early adopter of Aliro for universal digital key access across Android and Apple devices. The reviewer praises its convenient rechargeable battery, multiple unlock methods, and easy installation, though he notes issues with keypad brightness and the absence of a passage mode.
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