How does the Fitbit Flex Sleep Tracker work

Fitbit Flex (Fitness Tracker)

Fitbit Flex: The pioneer is running out of breath

Dennis Schöberl

In the test, we note the age of the Fitbit Flex. As one of the very first fitness trackers, it has a successful app, but it lags behind the competition due to the lack of a display and poor accuracy.

Very comfortable to wear
Good app
Very imprecise measurement
No display
Difficult operation

Fitbit Flex: One of the first

The Fitbit Flex was one of the first fitness trackers alongside the Nike + or the Jawbone (1st version). We have now sent the American fitness company's tracker, which costs around 90 euros, to our new test procedure for fitness trackers. The Fitbit Flex records your steps, from which the software uses specifications such as age, height, gender, weight and step length to calculate the distance covered, how many calories you have burned and the duration of activities on a daily basis. The Fitbit Flex also records sleep. To do this, switch to sleep mode by tapping the band twice before going to sleep. The tracker does not have a display, instead the bracelet comes with LED lights that show the progress of the day. The synchronization works via Bluetooth 4.0. If you don't have a Bluetooth 4.0 mobile phone, you have to use the included USB dongle. You can then analyze the data on the computer.
Shop recommendation for Fitbit Flex
Offer from | Prices include VAT plus shipping
Compare other offers

Fitbit Flex: App Features

How long and how deeply did you sleep? How many steps did you take? The Fitbit app (available for iOS and Android) reveals all of this the next day. In the personal settings, you can enter the stride length and the "stride length at walking pace" manually in the app. This should increase the accuracy of the distance display. With the Fitibit Flex you switch between the modes "dominant hand" and "non-dominant hand". The connection to the social networks Facebook and Twitter is also compulsory, in the internal ranking you compete with your training partners. Very good: The synchronization also works without the Fitbit Flex having to be online. In addition, up to eight alarms can be set in the app. The Fitbit Flex then gently wakes the wearer by vibration. Overall, the app is clearly laid out and offers various additional applications with which you can optimize your personal training.

Fitbit Flex: optics, comfort, battery

The inconspicuous Fitbit is not a piece of jewelry, the colors are - except for the red - quite subtle. Basically, the bracelet is very comfortable to wear. The Fitbit Flex is soft on the wrist and therefore does not interfere with normal activities. The competition, such as the LG Lifeband, is more noticeable here. The bracelet is delivered in two sizes and can be closed individually thanks to numerous eyelets. The battery should be sufficient for five days, this corresponds to our practical experience. Since the Flex does not have a display, the battery life should be significantly longer. For comparison: The Garmin Vivofit lasts a whole year despite the display.
Compared to other fitness trackers, the Flex does not shine with accuracy. On our test track, the Fitbit is an average of 26 paces off. The fitness bracelet also miscalculates the distance, despite the set stride length. The Flex also gave a mixed picture in the insensitivity test. It counts 200 steps when brushing your teeth.
The iHealth Wireless Activity and Sleep Tracker is larger than the Fitbit and is therefore more noticeable on the wrist. At around 45 euros, it's also significantly cheaper. The iHealth Fitness Tracker has a display and comes with two different bracelet colors. Alternatively, it can also be stowed in your trouser pocket thanks to the belt clip. In the test, the gadget scores with a very high level of accuracy and an extensive app. The tracker is compatible with iOS and Android.
Shop recommendation for Fitbit Flex
Offer from | Prices include VAT plus shipping
Compare other offers