Aqara is pushing smart home access into the next generation with the Smart Lock U400, a new deadbolt that brings Ultra-Wideband (UWB) to your front door for truly hands-free unlocking. With high-precision location awareness, the U400 is built to unlock at the right moment—when you arrive at the door—without forcing you to tap, type a code, scan a finger, or even pull out your phone.
One of the biggest draws is that the U400 is Aliro-ready, positioning it for a future where digital keys and access credentials work more smoothly across different devices, brands, and operating systems. Combined with Thread networking and Matter certification, the lock is designed for broad smart home compatibility and a more unified connected-home experience.
What makes UWB special on a smart lock is accuracy. Unlike approaches that estimate distance based on signal strength, UWB measures how long signals take to travel (often referred to as time-of-flight) to determine position with centimeter-level precision. In real-world terms, this means the Aqara Smart Lock U400 can unlock when you’re actually at the door, not when you’re merely nearby. It also adds spatial awareness by considering both distance and direction, helping the lock understand intent. For example, it can tell whether you’re outside approaching the entrance versus inside your home, reducing the chances of unintended unlocking.
Security is another key advantage. Because some wireless methods rely on signal strength, they can be more susceptible to relay-style attacks where signals are amplified to trick a system into thinking an authorized device is closer than it really is. UWB’s positioning methods, along with additional protections supported by the underlying standard (including features like Scrambled Timestamp Sequences), are designed to strengthen defenses against unauthorized access.
For Apple users, the U400 supports integration with home key in Apple Wallet. That means your iPhone or Apple Watch can act as a digital key, enabling unlock on approach—so your phone can stay in your pocket or bag while the door opens as you arrive. It also supports sharing access through the Apple Home app, and household residents can receive the home key automatically.
Of course, not everyone wants to unlock the same way every time, so Aqara includes multiple access options. Alongside UWB hands-free entry, the U400 supports NFC unlocking, fingerprint recognition, personal passcodes (including one-time and recurring codes), mobile app control, and voice assistant unlocking through Siri or Alexa when your hands are full. And for peace of mind, there’s still a traditional mechanical key for emergency access.
The U400 is also built for modern smart home setups. With Matter-over-Thread support, it works across major platforms such as Alexa, Apple Home, Google Home, Home Assistant, and SmartThings, making it easier to add the lock into routines and automations. Importantly, it can connect to a Matter platform with a Thread Border Router and the platform’s Matter controller—without requiring a dedicated Aqara hub—helping reduce extra hardware costs for many households. SmartThings support is also set to expand further, with Samsung Wallet support noted as coming in Q1 2026.
Everyday security gets a boost with an auto-lock feature powered by a built-in gyroscope, so the lock can secure the door after each use without needing an additional sensor. If you need the door to stay unlocked temporarily—during a move, while carrying groceries, or when guests are coming and going—you can toggle auto-lock using the Action Button on the interior panel.
For durability, Aqara designed the U400 with an IP65 rating to handle outdoor conditions like dust, splashes, and heavy rain. Power comes from a 4880 mAh rechargeable lithium-ion battery, with Aqara estimating up to six months of use per charge depending on how the lock is used—an eco-friendlier approach than disposable batteries.
A few compatibility notes are worth keeping in mind for buyers planning to use Apple Home features. Controlling the lock with Apple Home requires a Thread-enabled home hub such as Apple TV 4K, HomePod (2nd generation), or HomePod mini, or another compatible Thread Border Router. The lock can also pair with a Thread-enabled iPhone running iOS 18 or later. Unlock on approach requires iPhone 11 or later (with some exclusions) on iOS 18.5 or later, and Apple Watch Series 6 or later (excluding Apple Watch SE) on watchOS 11.5 or later. Tap-to-unlock has broader device support, working with iPhone XS or later on iOS 17.1 or later and Apple Watch Series 4 or later on watchOS 10.1 or later. NFC cards are sold separately, and battery life will vary with usage. An over-the-air firmware update may also be required to enable Aliro support.
With UWB precision, multi-platform smart home support, strong access flexibility, and a weather-ready build, the Aqara Smart Lock U400 is positioned as a forward-looking upgrade for anyone who wants faster, smarter, and more secure keyless entry.
