The core unit is the heart of the Mi Band. It is very small with dimensions of 14×36 x9mm and weighs just 5 grams.
The Xiaomi Mi Band can track your steps and your sleep. Unlike some fitness bands that lets you enter your sleep timing manually, this has automatic sleep tracking. The app downloaded from the Mi Shop is only in Chinese, but you can download the APK for the English version from the Mi UI form. Some phones might still show some details in Chinese depending on the device. Since this uses Bluetooth 4.0 LE to connect to devices, the firmware updates for the Mi band are pushed wirelessly.
The Mi Band immediately pairs with your smartphone over Bluetooth once you start searching for it using the app. During setup it asks for your gender, age, height and weight. You need to provide your Mi account so that all your data gets stored in your account, which can later be synced to your smartphone later if you want to switch your smartphone. It syncs data from the band to your smartphone only when you open the app.
Coming to sleep tracking, the Mi band automatically tracks your sleep when you are wearing it. If you find any issues with the time you slept and woke up, you can edit them manually. It tracks your sleep, including deep sleep, light sleep and awake time too based on your movements. You can share the sleep data easily, similar to the fitness tracking.
Since it uses just an accelerometer, it tracks the movement of your hands to calculate your steps, similar to most fitness accessories. Accuracy of sleep tracking is also not the best. Occasionally it shows that I’m awake in between deep sleep. It also shows something called “Ready to sleep”, as early as 8PM. It is not clear how the Xiaomi Mi Band wristband calculates if I’m Ready to sleep. It doesn’t track short naps in the afternoon or 20 minute power naps. If you forget to wear the band to sleep and place it still, it automatically thinks you are sleeping. So it is recommended to wear it always. The Mi Band doesn’t let you track your food like the Jawbone or Fitbit does.
Another interesting feature is the silent alarm. It uses the built-in vibration motors to gently vibrate to wake you up. Alarm can be accessed from the app’s menu on the top. The Smart Alarm feature wakes you up 30 minutes before the time you have set if you are in light sleep or in the ‘ready to wake up’ state.