Fitbit Flex or Jawbone Up: Which is the better fitness companion for your wrist?

As the summer goes on, so does the war for the ultimate fitness accessory and iPhone(s AAPL) companion. Both the Fibit Flex ($99.95) and the Jawbone Up ($129.99) want to help you win the battle of the bulge using your iPhone as a key weapon.

Apple has a strong interest in wearable computing, especially with how these devices fit in to the iDevice ecosystem, and both the Fitbit and Jawbone products are featured in many Apple Stores. Although Jawbone’s Up and Fitbit’s Flex are both wrist-based devices, they have some key differences that will interest body hackers. I’ve been using wearable fitness technology for over a year in my own training and evaluated how both of these gadgets work with Apple devices. Which one is best for you depends on your goals and objectives.

Fitbit Flex: It’s about the competition

I’ve been an active Fitbit user for years, migrating from the Ultra to the One and now to the Flex. What keeps me motivated is the installed base of Fitbit users also on the program. I’m constantly motivated to do more steps and keep up with the competition.

However, Fitbit users know one of the key frustrations with the device: it’s easy to forget you have it on and accidentally throw it in the wash or misplace it. Since the Flex is worn on your wrist, you are less likely to lose it. Additionally, it is water-resistant so you can wear it in the shower and do your normal activities without fear of water damage. To charge the Flex, you remove it from the wristband and place it in a USB charger.

This flexibility, pardon the pun, comes with a reduction in functionality, however. Gone from the Fitbit is a detailed display and stopwatch. While you can track your progress of steps throughout the day on the Flex with a series of five dots that indicates how close you are to the goal, you can’t know the exact number without the iPhone. Missing from the Flex is the altimeter (stair flight tracking) that both the previous Ultra and the current One track. The Flex will also track the length and quality of your sleep by detecting motion in the night. It will vibrate to wake you up.

Similar to the One, the device syncs using Bluetooth 4.0 with the iPhone 4S and above allowing users to check their progress throughout the day or in real time (I try to kick it up a notch while on the treadmill). The quick and easy sync almost makes up for the lack of display, something I suspect most users will only be slightly annoyed by in the Flex.

The Flex includes the same food diary and weight-tracker app the other Fitbit products have to keep you accountable during the day. The Fitbit data can be edited and appended via the Fitbit website so if you can’t track while away from the computer, you can add the info later. Third-party APIs offer additional features such as a more detailed food diary or an incentive program via Walgreens.

Jawbone Up: It’s about you

The Jawbone Up, after a rocky start, is a solid and effective fitness tracker. However, in spite of some unique strengths, the Up has a few notable downsides when compared with the Flex

One key difference between the Flex and the UP  is the Up does not sync via Bluetooth thereby giving it twice the battery life of the Flex (10 days in contrast to the Flex’s five days) and works with any iOS device running iOS 5.1 or greater. Syncing is instead done via the headphone jack and not in real time: you must remove the device in order to sync. Syncing takes just a few seconds and you can’t take any calls while syncing because the headphone jack is in use.

The band is water-resistant and can be worn all day. However, the Up electronics take up the entire band and thus can be damaged easier. In contrast, the Flex’s electronics are only a small portion of the band. My first Up failed due to possible over-flexing of the band because I tried wearing it on my ankle while working out.

Similar to the Flex, the Up tracks steps (but not stairs) as well as sleep with a vibrating alarm, but the Up adds an “optimal” wake-up window, analyzing your motion and waking you during the lighter portions of your sleep cycle rather than jarring you awake in the middle of deep sleep. Personally, I didn’t notice much of a difference here, but it’s a nice touch. The sleep function includes the ability to take a “power nap” and be woken at the optimal time as well.

While the Jawbone Up has a team function in which you can compete with others, I couldn’t find any friends using the device to test this function; I have several dozen using the Fitbit tracker. The Up will analyze your data and give you motivational messages via the iOS app. It’s called “Insights,” and the feature gives you suggestions based on the data it receives such as getting more sleep and compares your sleep and activities. The device will remind you to keep moving throughout the day via an optional “idle” alert that vibrates your Up if you sit for too long. You can even tell it your mood for the day and it will factor that into the analysis. The Up app is your motivator and coach throughout your day.


Credit: Thinkstock

The food diary is much more extensive in the Up and includes a larger database of food as well as the ability to add entries via a picture or scanning a barcode. By including so much data, the app keeps you very accountable as to what you eat. And similar to the Fitbit, the Up includes an API that allows a variety of third-party apps to extend the functionality and data analysis of the Up.

Unlike the Fitbit, however, the data on the Up is for native mobile apps only. It can be read or modified on an iPhone, iPad or Android but not the web unless you use third-party apps via the API. This can make tracking a bit tricky if you don’t have your iPhone handy.

What are the key similarities and differences?

Both the Flex and the Up sometimes have trouble detecting motions, in particular when on a bicycle or cardio machines such as an elliptical. I had to move my arms constantly or put them in my pocket to get them to register.

Because you can remove the Flex’s electronics, that also means you can change the color of the band after purchase. The Flex wristband is adjustable, while the Up offers only small, medium and large sizes with no swapping out of colors. Both are comfortable, but I had trouble with the clasp on the Flex getting in the way while typing, though it had a flatter profile overall than the Up.

Other than these differences the devices work ver
y similar and it’s a tough decision.

Which is best for you: Flex or Up?

If you are motivated by competition with friends, the Flex is a good choice. The app or the website lets you know how you are doing compared to your friends. Personally, I got very motivated by these comparisons — if I saw a friend was close to reaching one of my goals (steps, miles, etc.), I might park the car further away or take the dog for a longer walk. The social element for some is a key aspect of these devices so finding others that have these devices is an important consideration.

If you are more self-motivated, the Up may be a better choice because of the more detailed food diary and trend analysis of your sleep and steps, which can be very empowering. The insights and idle alarms are designed to motivate you and replace the motivation caused by competition. The Up is also compatible with older devices such as the iPhone 4 or 3GS because it uses the headphone port, unlike the Flex which needs Bluetooth 4.0 to interface directly with your phone.

Whichever device you choose you’ll still need to do the exercise so go out and enjoy the summer and use your iPhone (or Android device) to improve your fitness. What features, if any of these, Apple might include in the iWatch or other wearable tech remains to be seen.

Disclosure: Fitbit is backed by True Ventures, a venture capital firm that is an investor in the parent company of this blog, Giga Omni Media. Om Malik, founder of Giga Omni Media, is also a venture partner at True.