By Jason Snell

March 20, 2026 8:30 AM PT

Aqara UWB Smart Lock U400 Review: Beam Me Up

When it comes to smart locks, the goal is “Star Trek,” right? You should be able to walk up to your door and, swish!, it opens to greet you.

When I was a kid, “Star Trek” doors were amazing technology, but not too many years later, even the run-down supermarket in my hometown had automatic doors that opened when you approached them. Still, the dream lives on for the home. Most homes aren’t plausibly designed to have pocket doors that slide out of the way (and I have to think it wouldn’t be up to code), or even automatically swing open.

Okay, then, a dream downgraded: When it comes to smart locks, the goal is sort of “Star Trek,” in the sense that I’d like my door to unlock itself as I approach.

A few generations into this technology, we’ve bought and reviewed a bunch of smart locks, but the ultimate dream has not been fulfilled. Bluetooth-based locks can sort of do the trick, but since Bluetooth is a non-directional technology, there were all sorts of tricks (use geotagging, wait for the phone in question to leave the area, then enable lock-on-view) to make it happen. And it wasn’t very reliable.

Next came NFC locks, which work remarkably well but require you to press your phone or watch up against the lock. It works—I never carry a key for my house anymore, because my Apple Watch is my key—but it’s not exactly the Star Trek dream.

Finally, the future is here: locks with support for ultra-wideband (UWB) technology have begun to arrive, and since UWB offers precise positioning, it’s the first technology that truly offers the potential to have rock-solid support for walking right up to the door and having it unlock before you begin to reach.

I’m all in on the dream, so I bought the $270 Aqara UWB Smart Lock U400 (Amazon affiliate link) and installed it in my front door as my deadbolt, replacing an older NFC-focused smart lock. It’s been there for a couple of months now, and I’m happy to report that the “Star Trek” dream feels real.

After having owned a bunch of these, I’m struck by how robust Aqara’s lock motor is. It forcefully slides the deadbolt into place, which is helpful since my door can sometimes be slightly misaligned, and a little force from the bolt helps push it into place. (If it fails to mechanically lock, it makes a loud beeping noise to alert you that something’s wrong, which is very important if you’re walking out the door!)

I love the options the Aqara lock provides, too. Some smart locks I’ve used haven’t come with real keys, but Aqara’s does—the keyhole is normally hidden, but just drops down from the bottom of the entry panel. There’s a fingerprint sensor on the panel that can give you the Aqara equivalent of Touch ID, but only if you use the Aqara app itself. I added my print to the lock, but have never actually needed to use it. The lock also supports NFC, like my old lock, so older devices can be tapped against the pad to unlock the door. And yes, the display lights up so you can input a multi-digit code if you like.

But the star of the show is UWB unlocking, which uses your absolute positioning in space to unlock the door only when you approach it from the outside. (There’s a clever setting that lets you set what directions it will auto-unlock from, so that if a portion of your house is in front of your front door, it won’t unlock every time you walk toward the door in your garage.) Most of the time, the door audibly unlocks when I’m maybe a foot or less away from the door. Occasionally, I need to stand at the door for a moment, but rarely longer than a second or two. It worked just as well with my iPhone and with just my Apple Watch. It never unlocks accidentally when I approach it from other directions. It really does just work.

I also appreciate the Aqara lock’s approach to batteries. A not-so-fun fact about smart locks is that they require batteries. My previous smart locks have chewed up AA batteries over the course of a few months. Aqara has instead built a rechargeable battery into the lock that’s basically the size of an iPhone power bank. It’s been months, and my battery is still at 85%, so it is going to last a long time. But beyond that, it’s just an easy USB-C charge to top it back up.

You can either remove the battery and charge it wherever (while your lock stops working), or just plug in a power bank to the lock itself. Aqara cleverly suggests just putting the power bank in a bag and hanging it on the interior door latch while it charges the lock back up, which worked perfectly when I tried it.

As with many other locks, once you’ve got a smart lock attached to HomeKit, there are various automations you can run, though I haven’t ever found any of them to be particularly useful. For me, a good smart lock gives me confidence that the door is locked or will lock itself automatically (and I can check on my phone to confirm this), and opens easily.

I’ve never had a smart lock that opens more easily than the Aqara UWB Smart Lock U400. It’s not “Star Trek,” exactly, but it’s probably as close as I’m ever going to get.

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