Xiaomi Smart Band 10

The Xiaomi Watch S4 is a premium and highly customizable smartwatch that expertly blends classic aesthetics with advanced smart functionality, running on the modern Xiaomi HyperOS 2.

Design and Display Excellence

The Watch S4 features a sleek, circular design with a premium aluminum alloy frame and a sophisticated finish achieved through PVD technology. A defining characteristic is the innovative interchangeable bezel system, allowing users to snap different bezels (sold separately) onto the 47mm case, changing both the look and sometimes unlocking exclusive watch faces and functions.

The watch showcases a brilliant 1.43-inch AMOLED display with a sharp $466 \times 466$ pixel resolution. Crucially, the screen offers exceptional brightness, reaching up to 1500 nits (HBM) and a peak of 2200 nits, ensuring perfect visibility even under direct sunlight. Navigation is smooth and intuitive, utilizing both the responsive touchscreen and a newly added rotating crown with haptic feedback. The watch is also durable, featuring a 5ATM water resistance rating, making it suitable for swimming and shallow water activities.

Performance and Battery

Running on the efficient Xiaomi HyperOS 2, the Watch S4 provides a fluid user interface and seamless interaction with other Xiaomi devices via the Smart Hub. The 486mAh battery delivers exceptional longevity:

• Typical Usage: Up to 15 days of battery life.
• Heavy Usage (with Always-On Display/LTE): Approximately 3-5 days.

The watch supports quick charging via a magnetic charging dock.

Advanced Health and Fitness Tracking

The Xiaomi Watch S4 is a powerful fitness companion, equipped with a comprehensive set of sensors and over 150 sports modes, including professional modes like skiing with fall detection and Emergency SOS.

Key tracking features include:

• Heart Rate & SpO₂: Continuous, high-precision monitoring of heart rate and blood oxygen saturation ($SpO_2$) using an upgraded sensor and proprietary algorithm.
• GNSS Positioning: Features dual-band GNSS (L1+L5) supporting five major satellite systems (GPS, GLONASS, Galileo, BeiDou, QZSS) for superior accuracy and stability during outdoor runs and rides.
• Sleep and Stress: Advanced sleep tracking provides a detailed analysis, including a guided sleep improvement plan. It also offers all-day stress monitoring and breathing exercises.
• Skin Temperature: Includes a contact-based temperature sensor capable of detecting small changes for trend monitoring and enhanced female cycle prediction.

Connectivity and Smart Features

The watch offers full connectivity for a modern lifestyle:

• Bluetooth Calling: Integrated speaker and dual microphones with noise reduction allow for clear Bluetooth calling when connected to a smartphone.
• NFC: Supports NFC payments (availability of banking partners varies by region).
• HyperOS Integration: Facilitates smart home control and offers unique features like customizable wrist gestures (e.g., finger-snapping to reject calls).

The Xiaomi Watch S4 provides a premium, long-lasting, and highly customizable experience aimed at both the fashion-conscious user and the serious fitness enthusiast.