Instead, Fitbit Aria Air measures your weight (in imperial or metric units) and calculates your BMI using the height you entered when you created your Fitbit account. This is immediately synced with the Fitbit mobile app, allowing you to track changes over time and see how close you are to your goal weight. You can also easily see how lifestyle changes, such as increased exercise or improved sleep patterns, have affected your weight. The Fitbit Aria Air is available in black and white and, like nearly all smart scales, has a platform covered in tempered glass. In our tests, this seemed to be particularly prone to fingerprints. It is waterproof, so if it gets wet in the bath, it can be wiped with a dry towel, but we found that even rubbing it with a microfiber cloth left stubborn marks. As with any scale, there are a few general rules of thumb to improve the accuracy and longevity of the Aria Air: Fitbit recommends placing it on a hard, flat surface (no carpet), using it barefoot and dry, distributing the weight evenly on both feet, weighing it at approximately the same time each day under the same conditions and not to be exposed to extremely high or low temperatures, naked flames, or direct sunlight for long periods of time. We were surprised by the weight of the Fitbit Aria Air. Weighing in at 3.9 pounds (1.7 kg), it is not much different from a Wi-Fi scale like the Garmin Index S2 and much lighter than the Eufy Smart Scale C1 Bluetooth scale. but it’s worth keeping in mind if bathroom space is limited. Weighing yourself is just as simple. Place your scale on a flat hard surface; avoiding carpet, as this can interfere with the proper measurement. You’ll need to open the Fitbit app and tap the ‘Today’ tab before stepping onto the scale. Your weight will automatically sync via Bluetooth after you step off the scale. Tap ‘Save’ and your weight will be logged into your Fitbit profile. Your profile will save your previously logged weights which you can view in a graph format to see progress.