The Aqara U400 really changes the game when it comes to modern smart locks, especially with its ultra-wideband unlocking. It’s insanely fast, super smooth, and just works every time. I haven’t had a single issue since using it. It’s also a bit of a party trick—guests are always impressed when they see it unlock automatically, just like with the other smart features built into the lock.
The locking and unlocking is noticeably quicker thanks to the updated motor. Even compared to the U100—which was already fast—this feels snappier and more precise. Everything about it feels solid and intentional. I’m also a big fan of the refreshed design. The U100 already looked modern, but the rounded edges on the U400 and the new anti-peep keypad (where the numbers stay hidden until you activate it) really give it a premium vibe.
Another big win is the rechargeable battery. It’s just as reliable as the disposable batteries from the U100, but way more convenient. You can even hot-charge it, meaning you can plug it in and keep using it at the same time—huge plus.
Feature-wise, it checks every box: facial recognition, fingerprint scanning, passcodes, NFC cards, automations, USB access, remote control, and even a physical key if you want it. Managing access is easy too, whether you’re setting up permanent users or temporary access for guests.
Honestly, there’s not much to complain about. If I really had to nitpick, the lock is on the larger side—but that’s minor. If you’re shopping for a smart lock, this one pretty much ends the search. It does everything you’d want and then some. Another solid win from Aqara, and easily one of the best products in their catalog.
