Aqara U400
The lock that knows I’m coming. Why I finally replaced my Yale.
Heads up: if you buy through my links, I may earn a small commission. It doesn’t change what I say. [Did you buy this, or was it sent?]
The quick answer
Great if you
- Use Apple Home and want Home Key on your front door
- Run Home Assistant too, and want one lock in both
- Come home with your hands full, or have a cat who bolts
Skip it if you
- Want to finish setup without installing the Aqara app
- Need precise, up-to-the-minute battery reporting
- Want hands-free unlock on Android (Aqara lists UWB unlock for select iPhone and Apple Watch models)
What you need, feature by feature
Aqara’s compatibility list ↗| Feature | What it needs | What I used |
|---|---|---|
| Hands-free unlock (UWB) | A select iPhone or Apple Watch model, plus a Thread-enabled Apple home hub (e.g. HomePod mini or Apple TV 4K) | [My iPhone model] with the HomePod in my kitchen |
| Tap to unlock (Apple Home Key) | iPhone or Apple Watch with the key added to Wallet. Aqara says it works even when the device is powered off | Set up in Apple Home |
| Apple Home, Home Assistant, Google, Alexa | A Thread-enabled Matter controller for that app | HomeKit first, shared to Home Assistant |
| Samsung Wallet key | Samsung SmartThings | – |
| Codes, fingerprint, key | Nothing extra | – |
| Advanced settings | The Aqara app (codes, Night Latch, Do Not Disturb, approach direction) | – |
| Your door | A single-cylinder deadbolt. Other door dimensions may need modification | – |
Why the Yale had to go
I’ve been looking for a replacement for my Yale Assure SL for a very long time. The false reads, no physical key, the awkward backup: it had to go. For a $329.99 lock, it also leaned on a separate Wi-Fi bridge, so any power outage meant the lock instantly stopped reporting.
About a year ago I saw an ad for the Aqara U400, and it’s been on my radar ever since. I run both HomeKit and Home Assistant, and a lock that works natively with Apple’s Home Key was a must for this upgrade. Add a physical key, fingerprint, a keypad and UWB detection, and this lock got extremely interesting.
Putting it on the door
I’ve never replaced a lock in my life, and I was a tad intimidated by pulling one off my door. It went better than I expected.
My big worry was the door itself. There seem to be a couple of very common bore sizes (the hole the lock goes through), and I wasn’t sure mine was one of them. It was all fine. [Optional: add the bore and backset sizes the U400 fits, from Aqara’s spec sheet.]
Pulling off the old lock took a little elbow grease, mostly because of the old deadbolt strike plate in the door jamb. Once that was off, the new lock went in in about 8 minutes.
All I needed was a Phillips screwdriver. I used one of my Wiha precision drivers for the screws I was worried about stripping, and my Hoto electric screwdriver for the screws into the door and jamb.
Living with hands-free unlock
I have to say it: the hands-free unlock is life-changing. Some days you’re carrying lots of bags, or rushing to get into the apartment, and the lock just magically knows you’re coming and is ready to open. It also locks the moment the door closes. It’s amazing.
The lock just magically knows you’re coming.
I was a little concerned about it firing while I walked around inside. It’s smart enough to know where you are relative to the front of the door, and it doesn’t open just because you’re walking around the apartment.
Setup: HomeKit first, then Home Assistant
I paired it over HomeKit first, then shared it to Home Assistant. I did have to download the Aqara app, because setup was a little confusing without it, but once it was set up it was great. The Aqara app has the most tools for setting codes and customizing things.
This lock just works out of the box. The advanced features take a little tuning, but I was up and running within 20 minutes of opening the box, old lock removal included.
Codes, guests and the cat
Creating codes and users was seamless. I even wrote a little Home Assistant automation that generates a one-time guest code for when we have visitors.
As a cat parent, this lock adds a ton of peace of mind. I’m no longer constantly worried about whether the cat secretly got out.
One neutral point: my Yale had to be calibrated to know whether the door was ajar, and it would pretty regularly report locked and ajar, or stay unlocked when the door wasn’t ajar at all. The U400 uses a built-in gyro to know when the door has closed, and so far it’s been right every time. I added an Aqara Matter door sensor anyway, so I always have a plain open-or-closed answer in Home Assistant. I don’t need a fancy inclinometer to tell me how wide the door is open. A simple hall effect sensor will do.
How I tested it
Before a show opens, we run every cue and write down what happened. I tested the lock the same way, over [X weeks] of daily use.
| Cue | What I tried | How it went | Result |
|---|---|---|---|
| Q1 | Walk up with my phone, hands full of bags | Ready to open as I reach the door | Pass |
| Q2 | Walk around inside near the door | Stays locked | Pass |
| Q3 | Close the door behind me | Locks right away | Pass |
| Q4 | Pair to HomeKit, share to Home Assistant | Works; needed the Aqara app | Pass |
| Q5 | One-time guest code from Home Assistant | Works with a small automation | Pass |
| Q6 | Old lock off to new lock working | About 20 minutes | Pass |
| Q7 | Battery level reporting | Updates rarely | Watching |
Questions people ask me
Does it work with Apple Home?
Yes, natively, including Apple Home Key. I set it up in HomeKit first.
Do I need an Aqara hub?
I didn’t use one. It connects over Thread, through the HomePod in my kitchen.
Can I use it with Home Assistant too?
Yes. I paired it to HomeKit, then shared it to Home Assistant over Matter.
Is it hard to install?
I’d never replaced a lock before. Getting the old one off was the hardest part. The U400 itself went in in about 8 minutes with a Phillips screwdriver.
Does it know if the door is open?
It uses a built-in gyro to lock when the door closes, and Aqara’s app can warn you if the door is left ajar. I added an Aqara Matter door sensor anyway, for a simple open-or-closed answer in Home Assistant.
Do I need an iPhone for hands-free unlock?
Yes. Aqara lists UWB hands-free unlock for select iPhone and Apple Watch models, plus a Thread-enabled Apple home hub like a HomePod mini or Apple TV 4K. Keypad, fingerprint and key work without any of that.