Aqara U100 vs U400: Is Hands-Free Entry Worth It?
Automated research by Top10Scout editorial team · Not hands-on tested · Last verified 2026-10-05
Published · Updated
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Keep U100 if tapping Home Key or using its fingerprint reader is already convenient. Choose U400 when compatible hands-free approach unlocking would solve a daily problem. Carrying bags, handling a stroller or arriving in gloves can make that difference useful. Check the supported Apple device and Thread-enabled home-hub requirements first; UWB is not a feature that every phone automatically unlocks.
What does U400 change when you arrive?
What changes in daily use
| Decision | Aqara U100 | Aqara U400 |
|---|---|---|
| Phone-based entry | can be unlocked by tapping it with an iPhone or Apple Watch | the Smart Lock U400 unlocks as you approach with your iPhone or Apple Watch |
| Fingerprint option | Built-in Fingerprint Reader and Keypad | The Smart Lock U400 also features a built-in ergonomic fingerprint reader |
| Battery arrangement | Powered by 4 AA 1.5V batteries (included) | Powered by a rechargeable and removable lithium battery |
| Automatic locking | the built-in gyroscope enables the U100 to lock automatically after the door is closed. | With a built-in gyro sensor, the lock detects when the door is closed and locks automatically, no additional contact sensor needed. |
U100 already lets you tap a compatible phone or watch and provides fingerprint entry. U400 adds an approach-based UWB workflow. The practical difference is whether you need to present a device or touch the reader when reaching the door.
That can be a meaningful convenience when your hands are regularly occupied. If you normally arrive with a free hand and the current lock opens easily, the added feature has less work to do. We would decide from those repeated moments, rather than from the attraction of a new radio technology.
Which devices are required for hands-free unlocking?
Aqara’s current requirement is explicit: UWB unlock works with select iPhone and Apple Watch models and requires a Thread-enabled Apple home hub. Check the current supported-device and software list before buying. A device that supports an ordinary wallet key is not automatically proof that it supports this particular UWB approach mode.
U400 also uses Matter over Thread. Aqara says a Thread-enabled Matter controller from each ecosystem is needed for that ecosystem’s integration. If you plan to share the lock across platforms, include those controller requirements in the setup instead of treating Matter as a universal hub replacement.
Do not buy today around a promised future expansion to other devices. The useful comparison is the entry method your actual household can use now. U400 retains other unlocking options, but if those are all you need, a working U100 may already cover the job.
Does U400 remove the need to maintain batteries?
It changes the routine. U100 uses replaceable AA batteries. U400 uses a rechargeable, removable lithium battery and documents charging through the lock’s USB-C port without taking it offline, or removing the battery for separate charging.
Choose the arrangement you will actually maintain. Keeping appropriate spare batteries ready can be convenient; so can periodically bringing a power bank to the interior side of the door. Neither approach means the lock can be ignored indefinitely.
The headline months of battery life are manufacturer estimates under stated conditions. We have not run a matched endurance test, and different radio activity or use patterns can change the result. The clear documented change is disposable-cell replacement versus recharging, not a proven winner in time between maintenance.
Who should buy new, and who should keep U100?
For a new buyer with compatible devices who regularly benefits from hands-free entry, U400 is the more purposeful choice. Include the controller, intended battery arrangement and door installation in the complete purchase. For someone primarily wanting Home Key and fingerprints, compare the currently available U100 package before paying for approach unlocking.
For an existing U100 owner, the threshold should be higher. Replacing a working lock means buying another unit, fitting it and recreating the access routine. The difference between today’s shelf prices is not your full upgrade cost. Keep U100 unless the hands-free behavior or rechargeable system resolves a recurring inconvenience.
Both already document automatic locking after the door closes. Do not count that shared feature as a reason to replace the lock. After installation, configure access deliberately and test the actual approach path. This is a documentation-based convenience comparison, not a claim that either lock is more secure or recognizes every approach correctly.
What are the checked package prices?
The checked Aqara US lock-only references are $189.99 USD for the Gray U100 and $269.99 USD for the Black U400. The listed difference is $80.00. Keep the color and package scope in mind when following a purchase link. For an existing U100 owner, replacement means paying for the new lock, not merely this listed difference. Tax, shipping and promotions can change checkout totals.
Hands are occupied during everyday arrival
Consider U400 after confirming the supported device and home-hub setup. Its additional value is the approach-unlocking routine you will actually use.
U100 already opens the door comfortably
Keep it. Home Key, fingerprints and automatic locking remain useful, and replacing a complete working lock is a larger decision than comparing a pair of current shop prices.
Frequently asked questions
Does any iPhone support U400 hands-free entry?
No. Aqara specifies selected iPhone and Apple Watch models, software requirements and a Thread-enabled Apple home hub. Confirm your exact device against the current compatibility list before buying specifically for UWB approach unlocking.
Does U400 still support tapping Home Key?
Yes. The official product page documents Home Key tap-to-unlock as well as approach unlocking and other entry methods. Those are separate ways to use the lock; the presence of one should not be treated as proof your device supports the other.
Can U400 recharge without removing the battery?
Aqara documents charging through the lock’s USB-C port without taking it offline, and also describes removing the battery for separate charging. Plan whichever routine is practical at your door rather than assuming rechargeable means maintenance-free.
Would you replace a satisfactory U100?
Only for a useful new routine, most clearly compatible hands-free arrival. If tapping a device or using a fingerprint is easy already, keep U100. Its shared core functions make replacement difficult to justify simply because U400 is newer.
Official sources
Aqara Smart Lock U100: checked exact-model source and conditions — checked 2026-10-05
Aqara Smart Lock U400: checked exact-model source and conditions — checked 2026-10-05