The Xiaomi Watch S4 41mm features a 1.32″ OLED/AMOLED touchscreen with a resolution of 466 x 466 px and a pixel density of 320 ppi, and it supports an Always-On Display mode. The screen is protected by sapphire glass, though no branded damage-resistant glass is included. The case measures 41.2 x 41.2 mm with a thickness of 9.5 mm and a total volume of 16.12568 cm³, keeping the overall weight at a light 32 g. The watch band is replaceable, and the device carries a 5 ATM water resistance rating, making it waterproof for everyday use.
The watch includes a broad set of sensors for both health monitoring and navigation, covering a heart rate monitor, pulse oximeter for blood oxygenation tracking, and a body temperature sensor. Motion and orientation are handled by an accelerometer, gyroscope, and compass, while a barometer adds environmental awareness. Built-in GPS enables location and route tracking directly from the wrist. A cadence sensor and perspiration monitor are not included.
The Xiaomi Watch S4 41mm offers a thorough set of activity tracking capabilities, covering steps, distance, pace, elevation, and route tracking for a well-rounded picture of daily movement and workouts. Automatic activity detection and exercise tagging remove the need to manually log sessions, while calorie intake tracking rounds out the nutritional side of fitness monitoring. Sleep tracking is supported alongside detailed sleep reports, giving users a clearer view of their rest patterns. Water-based activities are also covered through a swim stroke counter, though the watch is not designed for diving.
The watch includes a cellular module with a single eSIM, allowing it to operate independently of a paired smartphone for calls and data. It is compatible with both iOS and Android devices and connects wirelessly via Bluetooth 5.4. NFC is also on board, and the watch supports the Galileo satellite navigation system for more accurate positioning. Wi-Fi and ANT+ are not supported.
The Xiaomi Watch S4 41mm is equipped with a 320 mAh rechargeable battery rated for up to 8 days of battery life on a single charge. It supports wireless charging, so no cable connection is required to power it up. The battery is not removable, and there is no solar charging capability.
On the health monitoring side, the watch tracks HRV, resting heart rate, and VO2 max, and provides a readiness and recovery level to help gauge daily preparedness. Fast and slow heart rate notifications are supported, though irregular heart rate warnings and ECG technology are not included. For everyday use, the watch delivers wrist notifications, call control, and the ability to answer calls directly, backed by a single built-in microphone. Vibrating alerts, a silent alarm, fall detection, and voice commands add further utility, while a stopwatch is on board for quick timing needs — a smart alarm is not available. 32GB of internal storage gives room for local content, and a fast GPS lock helps reduce the wait time when starting outdoor activities. Additional conveniences include a phone-finding function, a built-in camera remote shutter, and a one-year warranty. A front camera is not present.
The companion app is free to download, ad-free, and requires an account to use. It offers a solid range of tracking and management tools, including activity reports, an exercise diary, calorie burn counting, water intake tracking, weight tracking, and temperature tracking. Goal setting and achievements keep users motivated, while inactivity alerts help encourage regular movement throughout the day. Reproductive health features are also present, with period notifications, ovulation prediction, and cycle start date prediction. The app supports calendar sync, music playback, maps, widgets, and app personalisation, giving users meaningful control over their experience. On the other hand, coaching, route support, email export, and a barcode scanner are not available.
The watch includes a battery level indicator and supports passcode protection for basic security. It does not offer compatibility with Windows or Mac OS X, and there is no external memory slot or 3.5 mm headset jack.
