Aqara Smart Lock U400 Review

The Aqara U400's headline feature is one no rival is reported to offer yet: Ultra Wideband Apple Home Key. The lock unlocks hands-free as you walk up with an iPhone or Apple Watch, with no tapping or fumbling. AppleInsider describes it as the first and so far only smart lock with UWB Home Key support, and Aqara calls it one of the world's first. That gives it a clear identity. It is built first and foremost for Apple households who want the most seamless entry experience available.

It also covers the basics well beyond Apple users. You get a keypad, a built-in fingerprint reader, Matter over Thread connectivity and a rechargeable battery pack. The battery can be removed for charging or topped up in place over USB-C. Aqara also positions the lock as Aliro-enabled, which suggests UWB unlocking could reach other ecosystems later, though that is a forward-looking promise rather than something to buy on today.

Reviewers are consistent about the trade-offs. Both the inside and outside housings are large and blocky, and the lock sits at the pricier end of the market at $269.99.

If hands-free Apple Home Key is what you want, the U400 is effectively in a class of one right now. That alone justifies a strong recommendation for iPhone and Apple Watch owners. The supporting features also make it a well-rounded lock rather than a one-trick showcase:

• Multiple ways in suit a whole household: UWB proximity unlock, tap-to-unlock via Apple Wallet, the keypad and a fingerprint reader.
• According to Aqara, Home Key keys can be shared with family members, and tap-to-unlock still works when your iPhone or Apple Watch is powered off.
• Matter over Thread support makes it easier to fit into a broader smart home setup.
• The IP65 weather-resistance rating is reassuring for an exterior-facing device.
• A removable, USB-C rechargeable battery means you won't keep buying disposable cells.

The drawbacks are real, though:

• The chunky design will not suit every door or taste.
• Reviewers say battery life could be better, which matters on a device you rely on to get into your home.
• The price is high relative to conventional smart locks.
• Its ANSI/BHMA Grade 3 rating is the entry-level tier for physical security. That is acceptable for most homes, but buyers prioritising toughness may want more.
• Cross-platform UWB through Aliro is still an expectation, so Android users get less of the lock's standout feature today.

On balance, the U400 earns a high score for delivering a genuinely next-generation unlocking experience with solid fundamentals. It falls short of top marks because of its bulk, its battery life and its price.