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Door Locks · Head to head

Aqara Smart Lock U400 vs Nuki Smart Lock Ultra

Full Smart Door Locks comparison in 2026

Updated September 2026
Data from Amazon and official Aqara and Nuki sites.
2026 verdict
For a front door that should open with a finger, a code or an iPhone and nothing else to buy, the Aqara Smart Lock U400 is the smart lock to choose.
Aqara Smart Lock U400
Winner
Aqara Smart Lock U400
$269.99
Buy on Amazon USACheck price
Fingerprint, passcode, NFC and Apple Home Key are all built into its IP65 exterior, with one-time, periodic and anti-peep codes on top, while the Nuki Smart Lock Ultra needs its separate keypad before it takes a code or a fingerprint and carries no weather rating. The Nuki Smart Lock Ultra answers with built-in 2.4 GHz Wi-Fi next to Thread, a 2 year warranty, a compact 250g body, colour options and geolocation auto-unlock as you arrive. Both speak Matter and work with Apple Home, SmartThings and Home Assistant, though Google Home and Alexa need an Aqara hub on the U400. Choose the Aqara Smart Lock U400 for an all-in-one keyless deadbolt, and the Nuki Smart Lock Ultra for a European cylinder door you want to retrofit from the inside.
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FeatureAqara Smart Lock U400Nuki Smart Lock UltraWinner
Rating4.14.5Nuki Smart Lock Ultra
Weather ResistanceIP65NOAqara Smart Lock U400
Lock/Unlock SystemRemote, Bluetooth, Passcode, Fingerprint, NFC Tag, Apple Home Key, Physical KeyRemote, Bluetooth, Passcode, Fingerprint, Physical KeyAqara Smart Lock U400
One-Time PasswordYESKeypad requiredAqara Smart Lock U400
Periodic PasswordYESKeypad requiredAqara Smart Lock U400
Anti-peep PasswordYESNOAqara Smart Lock U400
Battery Life6 months6 monthsTie
ConnectivityBluetooth, Thread Protocol, Other2.4 GHz WiFi, Bluetooth, Thread ProtocolTie
IntegrationsGoogle Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant, MatterGoogle Home, Alexa, Apple HomeKit, Samsung SmartThings, Home Assistant, MatterTie
Emergency FingerprintNONOTie
DoorbellNONOTie

What the differences mean

Entry methods

The Aqara Smart Lock U400 has fingerprint, keypad, NFC and Apple Home Key in the lock itself. The Nuki Smart Lock Ultra opens by app, Bluetooth, auto-unlock or key, and only gains a code or a fingerprint once you add Nuki's keypad accessory.

Weather

The Aqara Smart Lock U400 is rated IP65 because its exterior half faces the weather. The Nuki Smart Lock Ultra has no rating: it sits on the inside of the door over a European cylinder, which is why it is not meant for exposure.

Wi-Fi and hubs

The Nuki Smart Lock Ultra has 2.4 GHz Wi-Fi built in, so remote access and voice assistants need no bridge. The Aqara Smart Lock U400 uses Bluetooth and Thread, so remote control rides on a Thread border router, and Google Home and Alexa go through an Aqara hub.

Security codes and alerts

One-time, periodic and anti-peep passwords are built into the Aqara Smart Lock U400, along with a tamper alert. The Nuki Smart Lock Ultra offers one-time and periodic codes only with its keypad, and has neither anti-peep codes nor a tamper alert.

Warranty

The Nuki Smart Lock Ultra is covered for 2 years. The Aqara Smart Lock U400 warranty is not documented in its listing, and its owners advise buying directly from Aqara to keep it.

Which one to buy if

Nuki

Nuki Smart Lock Ultra

Price unavailable right now
Buy on Amazon CanadaCheck price
  • + Rating: 4.5
  • - Weather Resistance: NO vs IP65
  • - Lock/Unlock System: Remote, Bluetooth, Passcode, Fingerprint, Physical Key vs Remote, Bluetooth, Passcode, Fingerprint, NFC Tag, Apple Home Key, Physical Key

What owners say

Owners of both locks rave about speed: a motor noticeably faster than the lock it replaced, and an install that most finish inside an hour thanks to a QR code that drops it into Apple Home. After that they talk about different things. Aqara Smart Lock U400 owners single out ultra-wideband hands-free unlocking, the door opening a moment before they touch the handle, plus the rechargeable USB-C battery; their complaints are a plasticky housing, a HomeKit and Thread setup that confused several of them and fingerprint enrollment that can be finicky. Nuki Smart Lock Ultra owners, many of them long-time Nuki users, talk about the premium build, built-in Wi-Fi making remote access work out of the box and customer support, and their gripes are small install quirks such as setting the cylinder length.

Price history compared

Every price change of both, in the same store, so the gap between the two lines is what one costs more than the other.

  • Aqara Smart Lock U400
  • Nuki Smart Lock Ultra

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Frequently Asked Questions

Which is better overall: Aqara Smart Lock U400 or Nuki Smart Lock Ultra?

The Aqara Smart Lock U400 for most buyers who want every way in built into the lock: fingerprint, keypad, NFC, Apple Home Key, anti-peep codes and an IP65 rating. The Nuki Smart Lock Ultra is the better choice for European cylinder doors and for anyone who wants built-in Wi-Fi and a 2 year warranty.

Nuki vs Aqara: what is the biggest difference between the Nuki Smart Lock Ultra and the Aqara Smart Lock U400?

How they fit the door. The Aqara Smart Lock U400 is a complete deadbolt with an exterior keypad and fingerprint reader. The Nuki Smart Lock Ultra is a retrofit that mounts on the inside over a European cylinder, and adds a keypad only as a separate accessory.

Does the Nuki Smart Lock Ultra have UWB hands-free unlocking like the Aqara Smart Lock U400?

Ultra-wideband unlocking is what Aqara Smart Lock U400 owners praise most. The Nuki Smart Lock Ultra offers hands-free auto-unlock through geolocation as you approach; UWB is not listed in its specifications.

Do both locks work with Apple Home, Google Home and Alexa?

Both support Matter, Apple Home, SmartThings and Home Assistant. The Nuki Smart Lock Ultra also works with Google Home and Alexa directly, while the Aqara Smart Lock U400 needs an Aqara hub for those two. Only the Aqara Smart Lock U400 supports Apple Home Key.

Who should buy the Aqara Smart Lock U400?

Apple households with a standard deadbolt who want fingerprint, keypad, NFC and Home Key entry in one weather-rated lock, and who already run a Thread border router.

Who should buy the Nuki Smart Lock Ultra?

Owners of European cylinder doors, renters who cannot replace the lock, and anyone who wants built-in Wi-Fi, geolocation auto-unlock and a 2 year warranty in a compact retrofit.

Full comparison table

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