Xiaomi Smart Door Lock M40: AI Dual-Camera & 4.94in Display

Xiaomi has opened pre-orders in China for the Smart Door Lock M40, a more accessible sibling to last month's M40 Pro. Priced at 3,299 yuan (about $464) for its launch offer, the M40 keeps many flagship features while trimming a few high-end extras to hit a lower price point.

Smarter peephole, clearer night vision

The headline feature is an AI-driven dual-camera peephole: a 3MP 175° wide-angle main camera paired with a 2MP 128° secondary lens. Together they deliver panoramic viewing, real-time video calls and instant notifications to your phone. Xiaomi added six infrared LEDs and multiple night modes to improve clarity in low light — useful for late-night deliveries or checking on a visitor from your couch.

Built for security and durability

The M40 uses a full-body automatic locking mechanism and a C-grade straight-insert mechanical cylinder designed to remain usable even if the external panel is damaged. Under the hood are a dedicated safety chipset, encrypted communications and reinforced structural elements to resist tampering and hacking attempts. In short: Xiaomi balanced smart features with basic physical security so the lock works even in edge cases.

• Front panel: 431 x 98 x 46 mm; rear panel height: 421 mm; weight: 5.18 kg
• Materials: metal frame with internal sensors for improved stability
• Operating range: -10°C to 55°C

Battery life, emergency power and connectivity

Power comes from an 8,000 mAh rechargeable lithium battery backed by four AA alkaline cells. Xiaomi says the internal lithium pack can last up to 4.5 months under typical use, while the AA backup can extend operation to about six months. Both panels accept USB-C emergency power input, and the lock also supports reverse wireless charging from compatible smartphones — a handy trick when you’re locked out and your phone has the juice.

On the networking side you get Bluetooth 5.3, NFC and Wi‑Fi 6 (2.4 GHz). The M40 runs on Xiaomi’s HyperOS platform and integrates with the Mi Home app, enabling remote access, instant alerts and two-way intercom. Controls extend beyond phones to tablets, certain Xiaomi TVs and even the company’s SU7 car system. It also supports voice and video interactions through WeChat.

Biometrics and unlocking options

The M40 supports 12 unlocking methods, including AI 3D facial recognition, AI fingerprint recognition, NFC cards, numerical passcodes and app control. Compared with the Pro model, the M40 removes palm-vein recognition and uses a slightly smaller 4.94-inch touchscreen, but it retains most of the convenience features home users expect.

Beyond the lock, Xiaomi continues to expand HyperOS into everyday devices — from a smart in-car humidifier compatible with SU7 and YU7 to a new 12 kg front-load washing machine offering 25 smart wash modes. For buyers who want smart home continuity, the M40 slots neatly into Xiaomi’s growing ecosystem.

Whether you prioritize a sharp peephole, long battery life or HyperOS integration, the M40 aims to deliver flagship sensibilities at a lower cost. Pre-orders have already begun in China; global availability and pricing will likely follow depending on demand.

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