Fitbit Flex Fitness Band Review

Wristband Wireless Activity and Sleep Monitor

Fitbit Flex
Fitbit Flex. Fitbit

The Fitbit Flex created the craze in wearing wristband activity monitors. The Flex has a Fitbit activity monitor encased in a flexible band. You can wear it all day and all night to track steps, distance, calories burned, and sleep quality. It syncs wirelessly with PC or Mac computers and/or a phone app for iOS or Android. It differs from the Fitbit Charge and the Fitbit Charge HR in that the Flex doesn't have a numerical readout on the band, just LED lights to show your progress.

Fitbit Flex On the Wrist

I've worn every model of Fitbit since they debuted. I love their online Dashboard and app to view your activity, diet, health and sleep stats. This is the first model designed to be worn all day and all night on your wrist. The sensor slips into the flexible wristband. Snap the wristband on with an adjustable clasp.

Both small and large wristbands are included, as is the USB charging cable and a wireless USB dongle for your computer (PC or Mac). You can buy other fashion colors and swap them whenever you wish.

You will have to remove the sensor from the wristband to charge it approximately once every five days. It is water-resistant so you can wear it in the shower or bath and can be submerged up to 10 meters (33 feet).

The Flex band is flexible and comfortable to wear compared to rigid bands such as the Nike+ Fuelband, Jawbone UP and Polar Loop. That's important for something you are supposed to wear continuously.

Although they say it won't be as accurate, you can carry the Flex in your pocket if you didn't want to wear the wristband. I've done that with similar trackers and they work just fine that way. It's an option in case the Flex doesn't match your outfit.

Setting Up the Fitbit Flex

First, charge the Flex for up to three hours.

You can set up the device with either a computer or with the iOS or Android app.

To set it up with​ a computer, you plug in the USB dongle and download the Fitbit Connect software to run. Then whenever you are within a few feet of your computer, it senses the Fitbit and wirelessly syncs the data automatically.

You can do all of the set-up with the iOS or Android phone apps if you have a Bluetooth compatible device, or pair it with those devices after setting it up on the computer. With the phone apps, you have a choice to have it sync only when you open the app, or to sync in the background.

During set-up, select whether you are going to wear it on your dominant wrist (such as the right wrist if you are right-handed) or the non-dominant wrist. This will make the readings more accurate. You can also set your walking and running stride length via the online Dashboard (Edit Profile function) for better distance accuracy. How to Measure Your Stride

I find the Fitbit setup to be easy and painless.

You can only sync one Fitbit to your account. If you have been tracking any other Fitbit devices, such as the Fitbit Zip or the Fitbit One, then you will have to choose whether you will be tracking the Flex with your account or whether you want to create a new account for the new device.

Viewing Your Activity with Fitbit Flex

The Fitbit Flex has no display other than five LED white lights. You will set your daily goal and then each light represents achieving 20% of that goal. If your goal is 10,000 steps per day, then the first light will glow steadily at 2000 steps and a second light will be blinking.

The lights only come on when you tap the Fitbit Flex twice, so you won't be roaming around with lights glowing continuously.

You can see your actual numbers at any time if you have passed by the computer where the USB dongle is plugged in, or you sync with the phone app.

When you reach your goal, the Flex vibrates in celebration.

This was a fun surprise for me. I liked knowing I had met the goal for the day.

What Fitbit Flex Tracks and Doesn't Track

Steps But Not Workouts: Fitbit tracks all-day steps. There is no function for tracking only workout steps. You are able to view your Activity Graph on your web Dashboard on the app. But you don't get stats for specific workouts. You can add non-step activities or workouts where you didn't wear your Flex to your total with the web Dashboard or app. You can also use the mobile app's Track Exercise function and your phone's GPS to map, measure and time a walk, run or bike workout.

Calories: The calorie number includes the calories you burn at rest, so first thing after getting up you will see you have already burned some calories while asleep. This calorie count can be used to match the calories you eat with the calories you burn off all day. You can use the Dashboard to set a food calorie goal and a calorie burn goal for weight loss.

Distance: The distance display is based on your steps length and step count, it is only an estimate.

Sleep: To track sleep, you tap on the Flex for a couple of seconds until it vibrates and flashes. Just wear it on your wrist. In the morning, tap it again repeatedly until it vibrates and flashes again. You can view your total time in bed, time asleep, and number of times awake during the night, plus a sleep graph.

No Stairs/Floors: The Fitbit One, Fitbit Charge, Fitbit Charge HR and Fitbit Ultra also track how many floors of stairs you climb each day. The Flex and the Fitbit Zip do not.

Active Time: Are you getting the 30 minutes of moderate-to-vigorous exercise recommended each day? The Fitbit Flex counts active minutes if you take enough steps during that minute and adds them to this total.

Fitbit Dashboard and App

Fitbit is a favorite of mine for tracking your diet and health stats.

Food and Water: You can use it's food diary to log the food you eat and set a diet plan. You can also track your water intake.

Weight: You can log your weight and see graphs over time. Fitbit also has an Aria scale which sends the data wirelessly.

Friends: You can add Friends to your Dashboard if they have a Fitbit account and compare your daily average and weekly step totals, send them Cheers, Taunts and messages.

Bottom Line on Fitbit Flex


  • Comfort: I found the Flex to be the most comfortable of the wristband activity monitors I have been wearing
  • Display: The five light display may be all of the info you really need to see how you are progressing towards your daily goal.
  • Mobility: If you use it with the app and a Bluetooth-connected device, you have quick access to your data and are not reliant on uploading it via a computer.
  • You can slip the sensor out of the band and carry it in a pocket if you prefer, although Fitbit doesn't tell you that you can do that.
  • The Fitbit app and Dashboard play well with other apps. You can see which of your favorites for tracking your walks and health stats communicate with Fitbit and vice versa. These include Endomondo, MapMyWalk, SparkPeople, Microsoft HealthVault, MyFitnessPal, and Walgreens Balance Rewards.


  • No time of day, step count, distance or calorie display: You can't replace your watch with this wristband.
  • You can't use the distance estimate to help navigate or the calorie count to manage your diet without opening the app or being near your computer to sync the data and view your Dashboard.
  • You can't track individual workouts with the Flex. You can only add them via the app or online Dashboard manually or by using the app's GPS Track Exercise function. If you want workout tracking on your band, the Fitbit Charge is a better choice, you can start and stop the tracking and see stats for just that workout.
  • Some users have problems with the clasp coming undone. It doesn't have a built-in "keeper" loop, so if this happens, it just falls off. You may want to buy a Bitbelt security loop or find the right-sized o-ring at a hardware store to keep your band secure.

If a wristband works best for you and you want diet tracking and sleep tracking, the Fitbit Flex is an excellent choice.

I like having my numbers visible without having to view them on an app, so I prefer the Fitbit Charge and Fitbit Charge HR fitness bands, or the Fitbit One or Fitbit Zip worn on my waistband or in a pocket.

Disclosure: Review samples were provided by the manufacturer.

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