Fitbit Flex Fitness Band Review

Fitbit Flex

The Fitbit Flex created the craze in wearing wristband activity monitors. The Flex has a Fitbit activity monitor encased in a flexible band. The Flex doesn't have a numerical readout on the band, just LED lights to show your progress. It syncs wirelessly with a phone app or computer. You can view all of your data on the app or online dashboard. You can wear it all day and all night to track steps, distance, calories burned, and sleep quality.

The Fitbit Flex has been discontinued as of 2017 and replaced with the Fitbit Flex 2. The Flex 2 adds automatic sleep detection, automatic detection of exercise workouts, reminders to move, call and text notifications, and is swim-proof.

Fitbit Flex on the Wrist

This was 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 receiver 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 2 is swim-proof and automatically detects swimming.

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. The Flex 2 has progressed so they tout wearing it in a pendant in addition to on your wrist.

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 phone app.

To set it up with a computer, plug in the USB receiver 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-ups with the phone app 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 throughout the day.

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.

You can switch which Fitbit device is linked to your account, or even choose to only use your phone's built-in step counter if you don't want to wear your device for a while.

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 percent 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.

What Fitbit Flex Tracks and Doesn't Track

  • Steps and Workouts: Fitbit tracks all-day steps. There is no function for tracking only workout steps with the Flex, but the Flex 2 automatically detects and tracks walking, running, biking, and swimming workouts. You are able to view your Activity Graph on your online Dashboard on the app, but you don't get stats for specific workouts with the original Flex. 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. The Flex 2 doesn't require this, it automatically detects sleep. You can view your total time in bed, time asleep, and a 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, Alta, and 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 makes it convenient to track your diet and health stats and to participate in challenges with friends.

  • Food and Water: You can use the 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 that 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. You can also participate in group challenges, including daily, workweek, and weekend challenges.

Bottom Line on Fitbit Flex


  • Comfort: The Flex is comfortable with the wristband activity monitors
  • 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 mobile 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 on the 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 Flex 2, Fitbit Charge 2, or Fitbit Alta is a better choice.
  • 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.
  • The Fitbit Flex has been discontinued as of 2017.

If a wristband works best for you and you want diet tracking and sleep tracking, the Fitbit Flex is an excellent choice, although you should buy the current model, the Flex 2.

If you like having numbers visible without having to view them on an app, so you may prefer the Fitbit Charge 2 or Fitbit Alta fitness bands, or the Fitbit One or Fitbit Zip ​that is worn on your waistband or in a pocket.

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