Fitbit Flex Review

Fitness trackers have interested me since the Fitbit Classic was announced in 2008. Two years ago I finally joined the party and purchased the Fitbit Ultra. I was amazed at the amount of data the device was able to capture. Not only did it count steps, it measured distanced, steps taken, stairs climbed, and sleep activity. As someone who loves statistics, I was immediately thrilled with the device. Unfortunately the Ultra was a clip-on device and I often forgot to wear it. Eventually I stopped using it altogether. At CES this year Fitbit announced a fitness tracker that can be worn on the wrist. I have anxiously been waiting to get my hands on a Fitbit Flex and finally have one. Let’s get started with the Fitbit Flex review.

The Device

I don’t wear a watch so I was slightly concerned the Flex would irritate me. It doesn’t. The device is very lightweight and comfortable on my wrist. Most people will have no problems using the small or large wristband included in the package. I tested the water resistance of the Flex today. I can confirm that after a long shower it still works. My only concern is with the clasps on the band. While I was sleeping last night it became undone and fell off my wrist. If a sedentary activity like sleeping can unlock it, I imagine this could be problematic for more intense activities. Since the device can be removed from the wristband I imagine Fitbit will release more secure wristbands in the future.

The Fitbit Flex has many of the same features of its predecessor. It tracks steps taken, distance traveled, calories burned, active minutes, hours slept, and quality of sleep. It also sports a new silent wake alarm. Unlike previous versions, the Flex does not count stairs climbed. If this is an important feature for you, then look elsewhere.


Some early reviews have blasted the device on its accuracy. For me the verdict is still out. Because the device is worn on the wrist obviously it will incorrectly count some steps. After 10 minutes of getting my ass kicked in MW3, the Flex recorded over 200 steps. If exact accuracy is critical to you, make sure you wear the device on your non-dominant hand and remove it when necessary.

I tested the distance accuracy with two 10-minute walks and Runkeeper. The difference between the two is not enough for me to fret about.

Trip 1
Fitbit: .58 Miles
Runkeeper: .62 Miles

Trip 2
Fitbit: .54 Miles
Runkeeper: .58 Miles

Additional Flex Features

Sleep tracking is a bit of a novelty for me. To activate sleep mode, tap the Flex until it vibrates and the two outer lights illuminate. Repeat the process to deactivate sleep mode. I found it easier to rest my wrist on something when enabling or disabling this feature.

Silent wake alarm works surprisingly well. You can set the alarms via the web dashboard or mobile application. Like standard alarms you can set multiple times and schedules. Two vibration modes are available. The standard alarm vibrates twice and the continuous alarm vibrates until you turn it off. I am a heavy sleeper and need the continuous alarm.

iOS Fitbit Application

The Flex syncs wirelessly with mobile applications. Since I use an iPhone I can only comment on the iOS app. It needs some work to put it simply. Reviews on the App Store make it sound unusable. I have not found that to be the case.

Activity tracking on the app seems more complicated than it needs to be. I would also like to see a notification on the phone or Flex when an activity duration has ended.

Being able to control the silent wake alarm on the app is great. Unfortunately the only option is to set the standard alarm. I hope not including the continuous alarm was an oversight and not a technical limitation.

Logging food and water consumed is not something I am interested in. It is always a cumbersome task and I have yet to find an application that simplifies it. If you are interested in these features, Fitbit has made them on a par with other calorie tracking services.


I’m excited to be using a fitness tracker again. Is the Flex perfect? No. Since I own the Fitbit Aria Wi-Fi scale I am inclined to stick with the Fitbit brand. Linking the Aria and Flex to your Fitbit account unleashes a powerful combination of health and fitness stats. Hopefully the next iteration of the Fitbit will make cheeseburgers taste not so damn good.

Comments (6):

  1. Craig

    May 10, 2013 at 7:40 am

    Thanks for the review…. I also own the scales and looking to stick with fitbit…

  2. Ryan Eakin

    May 17, 2013 at 2:06 pm

    I’ve been debating on buying one but if you did I think I’ll just bite the bullet now lol. Thanks for the review.

  3. Cute Counselor

    February 10, 2014 at 12:51 pm

    I got the Force and love it. I know they are glorified pedometers and you can make of it as you’d like, but I am happy I did it. (even if just to remind me to get up and move)

    • Zach Matthai

      May 10, 2014 at 2:39 pm

      I’ve been thinking about upgrading to the Force. Glad to hear you enjoy it 🙂


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