Most smart locks still ask you to do something — tap your phone, press a finger, punch in a code. Ultra-wideband (UWB) changes that. It lets a lock sense exactly where your phone is in space, so the door can unlock as you walk up to it with your phone still in your pocket or bag. In Aqara’s entire lock range, only one model has it: the Aqara Smart Lock U400.
This guide explains what a UWB smart lock actually does, why it matters for hands-free entry in Singapore, and how the U400 works as both a front-door lock and — uniquely — a UWB-enabled gate lock.
What is UWB (ultra-wideband), and how is it different from Bluetooth and NFC?
Ultra-wideband is a short-range radio technology that measures distance and direction with very high precision. Where Bluetooth can only tell that a phone is roughly nearby, and NFC only works when you physically tap a device against the reader, UWB knows how far away your phone is and which direction it is moving. That spatial awareness is the key to genuine hands-free unlocking.
Because a UWB lock can tell the difference between you approaching from outside and you simply walking past on the inside, it can unlock at the right moment without the false triggers that make Bluetooth-only auto-unlock unreliable. Apple builds UWB into iPhone 11 and later and Apple Watch Series 6 and later, and the U400 uses UWB together with these devices to detect your approach.
The Aqara U400 — the only Aqara smart lock with UWB
Aqara describes the Aqara U400 simply: it “unlocks as you approach with your iPhone or Apple Watch — a hands-free, privacy-preserving entry experience.” To use the approach-unlock feature you need an iPhone 11 or later or an Apple Watch Series 6 or later, plus a Thread-enabled Apple Home hub. No other Aqara lock offers this — the U300, U200, U50, U100 and the D-series locks all have fingerprint, keypad or NFC entry, but none of them have UWB.
UWB is the headline, but the U400 is far from one-trick. It also unlocks by Apple Home Key tap (which keeps working even when your iPhone is out of battery), by fingerprint (it stores up to 50 prints and reads in about 0.3 seconds), by PIN or password with anti-peep protection, by NFC card, remotely through the Aqara Home app, and with a traditional mechanical key — two are included in the box. The lock runs on Matter over Thread, so it also works with Apple Home, Google Home, Amazon Alexa, Samsung SmartThings and Home Assistant through a Thread hub.
It is powered by a removable rechargeable Li-ion battery that lasts up to about six months per charge, with a USB-C emergency charging port for the rare day you forget, and the outer panel carries an IP65 weatherproof rating.
The U400 as a front-door lock in Singapore
Mechanically the U400 is a US-style single-cylinder deadbolt retrofit, designed for a 60mm or 70mm backset and a door thickness of roughly 35–55mm. That makes it an excellent fit for many condo flush doors and landed-home timber doors — but it is not a universal fit. A lot of Singapore HDB and condo main doors use a mortise-and-deadbolt setup rather than a single-cylinder deadbolt, so the U400 is not the right lock for every front door.
If your main door uses a mortise lock — common on HDB and many condo main doors — the U400 is not the right fit, and a dedicated mortise smart lock is the correct category instead. The simplest way to be sure is to send us a photo of your door and its existing lock on WhatsApp at +65 9051 7063 — we will confirm the right lock before you order. Every Aqara lock we sell is covered by a 2-year onsite warranty by the Aqara Service Center in Singapore.
The U400 as a gate lock — UWB hands-free at your gate
Here is where the U400 does something no other Aqara lock can. On a suitable metal gate — an HDB grille gate, a condo gate or a landed-property perimeter gate — the U400 can be fitted using a gate lock box. Gate construction varies a lot, so not every gate will take it and the fit always needs to be confirmed first. But where it fits, the U400 is the only Aqara lock that brings UWB hands-free approach unlock to a gate.
That matters because the purpose-built Aqara U500 Gate Lock does not have UWB. So if your priority is walking up to your gate and having it open with your phone still in your pocket, the U400 is the lock that delivers it. One honest caveat: like any deadbolt-style lock repurposed for a gate, the U400 reads from the outside, so for exit from the inside you would use the Aqara app or add a small wireless release switch on the inner side. To check whether your gate can take a U400, message our team on WhatsApp at +65 9051 7063.
The best of both: U400 on the door, U500 Gate Lock on the gate
If you have both a gate and a main door, the strongest setup for an iPhone household is to use each lock where it is strongest. The Aqara U500 Gate Lock is purpose-built for gates: it has a fingerprint reader and a key cylinder on both the inside and outside, so there is no reach-through risk and no need for a separate exit switch. It adds gyroscope auto-locking, an IP65 weatherproof outer panel, a built-in doorbell button and Apple Home Key. What it does not have is UWB.
So pair the two: the Aqara U400 with its UWB hands-free unlock on your main door, and the U500 Gate Lock on your gate. Aqara’s “One Tap, Dual Unlock” feature lets you pair a gate lock with another Aqara smart lock so a single action opens both your gate and your front door. Combined with the U400’s approach detection, you can walk up to your home with your phone in your pocket, the U400 releases, and the paired gate opens with it — gate to door without touching a thing. Because both locks run in the Aqara Home app over Matter and Thread, our team can set up the pairing and the routine for you.
Using a lock on a Singapore gate: U400 vs U500 Gate Lock
Both locks can secure a gate, but they solve the problem differently. Here is the head-to-head for Singapore buyers.
| Feature | Aqara U400 | Aqara U500 Gate Lock |
|---|---|---|
| UWB hands-free approach unlock | Yes — the only Aqara lock with it | No |
| Access on both sides of the gate | Outer reader; inside via app or added switch | Fingerprint & key on both sides |
| Exit from the inside | Aqara app, or add a wireless release switch | Inside fingerprint, PIN or key — no extra switch |
| Weatherproofing | IP65 outer panel | IP65 outer, IP54 inner panel |
| Auto-lock | Gyro-sensor auto-lock | Gyro-sensor auto-lock |
| Apple Home Key | Yes | Yes |
| Price (Singapore) | $649 | $799 |
| Best for | iPhone homes wanting hands-free entry on a door or a suitable gate | A dedicated gate needing secure two-sided access |
Cross-bore deadbolt locks such as the B50, U50 and U100 can also be repurposed onto a gate, but like any deadbolt on a gate they need a wireless release switch fitted on the inside for exit, and none of them have UWB. The U400 is the one to choose when hands-free approach unlock is the goal; the U500 Gate Lock is the one to choose when you want a true two-sided gate lock.
What you need to run UWB hands-free unlock in Singapore
- An iPhone 11 or later, or an Apple Watch Series 6 or later — these have the UWB hardware the U400 talks to.
- A Thread-enabled Apple Home hub (a HomePod mini, HomePod 2nd generation, or an Apple TV 4K with Thread) for Apple Home Key and Matter-over-Thread features.
- An Aqara Thread/Matter hub if you want the full Aqara Home feature set and remote control. Basic local functions also work over Bluetooth.
Not sure what you already have at home? Send us a quick message on WhatsApp at +65 9051 7063 and we will tell you exactly what you need.
Frequently asked questions
Does the Aqara U400 really unlock without me touching my phone?
Yes. The U400 uses ultra-wideband (UWB) to sense your approach and unlock as you walk up to the door, with the phone in your pocket. You need an iPhone 11 or later or an Apple Watch Series 6 or later and a Thread-enabled Apple Home hub. Fingerprint, PIN, Apple Home Key tap, the app and a mechanical key all work too.
Is the U400 the only Aqara lock with UWB?
Yes. No other Aqara lock has UWB — not the U300, U200, U50, U100, the D-series, or even the purpose-built U500 Gate Lock. The U400 is the only one that offers hands-free approach unlock.
Can the Aqara U400 be used on a gate?
On a suitable metal gate it can be fitted with a gate lock box. Gate construction varies, so not every gate will take it and the fit must be confirmed first. Where it fits, the U400 is the only Aqara lock that brings UWB hands-free unlocking to a gate.
What is the difference between the U400 and the U500 Gate Lock for a gate?
The U500 Gate Lock is purpose-built for gates, with a fingerprint reader and key on both sides and no need for a separate exit switch — but it has no UWB. The U400 adds UWB hands-free approach unlock. Many Singapore homes pair both, one on the gate and one on the main door.
Can one action open both my gate and my front door?
Yes. Aqara’s One Tap, Dual Unlock feature pairs a U500 Gate Lock with another Aqara smart lock so a single trigger opens both the gate and the front door.
Do I need a hub for the U400?
For UWB hands-free unlock, remote access and Matter features, yes — you need a Thread-enabled Apple Home hub and, for the full Aqara feature set, an Aqara Thread hub. Basic local features work over Bluetooth without a hub.
Is there a Singapore warranty?
Yes. Every Aqara lock we sell comes with a 2-year onsite warranty by the Aqara Service Center in Singapore.
The bottom line
If you want true hands-free entry and you live in an iPhone household, the Aqara U400 is the Aqara lock to buy — it is the only one with UWB, and it works as a hands-free lock on your main door and, where the gate suits it, on your gate too. For a dedicated gate with secure two-sided access, pair it with the Aqara U500 Gate Lock and link the two with One Tap, Dual Unlock. Browse the full range of Aqara door locks, and to find the right setup for your door and gate, send us a photo on WhatsApp at +65 9051 7063.