XiaomiMi Smart Band 9

How we test ease of use

Ease of use includes how easy it is to set up the device, sync it with a phone or computer, what it's like to wear and use on a daily basis and the quality of the accompanying app (how customisable the app or computer software is, how well information is displayed and how good it is for setting goals and challenges)

How we test quality of sleep function

Ease of setting up, activating and understanding data from the sleep function and using the sleep-cycle alarm (for models with this feature)

How we test battery life

How good the battery life is per charge, how long the battery takes to charge between uses and the effect on a paired phone's battery life

How we test fitness tracking

The fitness tracking overall rating includes how accurate data is for steps, distance (not using a paired phone's GPS), calories burned and heart rate, how consistent the device is and what the sleep function is like (for those models that have one). Individual accuracy ratings for the different activities are made up of step, distance and calorie accuracy. The accuracy of the different functions are summarised for walking, running and our routine of daily tasks (including carrying shopping, sweeping and reading a magazine). Heart-rate accuracy (for models with built-in monitors) is measured at rest and during high and low intensity activity.