Fitbit Flex Wireless Wristband Review

Introducing Flexbit Flex

There are two types of wearables that folks will like to use them to its fullest potential- a smartwatch and a wireless fitness tracking wristband. I have started to review these wearables, starting with the Fitbit Flex. Along with its app, the Fitbit Flex allows its users to track their day-to-day activities and help to keep a track on exercise, sleep, food & water consumption, and some more.

Packaging and Specification

Fitbit provides two wristbands, a sync dongle that tracks your activity and syncs with your smartphone, a wireless dongle (not seen in the images) and a USB charging cable. The packaging gives a good amount of detail about the tracking capability of the Fitbit Flex. This tracker app works with iOS devices (iPhone 4s/iPad 3rd gen and above, leading Android devices). Though its not mentioned in the packaging, it is compatible with Windows-based mobiles.

The actual specs are as follows:


  • Small Fits Wrists= 14 cm – 16.5 cm
  • Large Fist Wrists= 16.5 cm to 21 cm
  • Width= 15.2 mm

Sensor and Components

  • 3-axis Accelerometer
  • Vibration Motor


  • LED display with 5 white indicator lights
  • Tap twice to see progress against your Main Goal
  • Tap rapidly for 1-2 seconds to start or stop sleep tracking

What’s Included

  • Removable Fitbit Flex Tracker
  • 2 Wristbands (Small and Large)
  • Charging Cable
  • Wireless Sync Dongle

Water Resistance

Flex has been tested up to 1 ATM meaning it is sweat, rain and splash proof. However, the device is not waterproof. We also recommend taking Flex off before showering because, as with any wearable device, it’s best for your skin if the band stays dry and clean.


If the band gets wet or if you sweat it, remove and completely dry the band before putting it back on. Clean the band with a mild soap-free cleanser like Cetaphil Gentle Skin Cleanser or Aquanil. Give your wrist a rest by taking the band off every now and then.


The Flex wristband is made of a flexible, durable elastomer material similar to that used in many sports watches. Flex also has a surgical-grade stainless steel clasp.

Battery and Power

  • Battery Life: Up to 5 days
  • Battery Type: Lithium- Polymer
  • Charge Time: One or Two hours
  • Radio Transceiver: Bluetooth 4.0

Environmental Requirements

  • Operating temperature: -20° to 45° C
  • Maximum operating altitude: 9.144 km


  • Tracks 7 days of detailed motion data, minute by minute
  • Tracks daily totals for past 30 days


  • Flex syncs automatically and wirelessly to tablets, computers and 150+ leading iOS, Android and Windows smartphones using Bluetooth 4.0 wireless technology.
  • Syncing range: 6 meters
  • Syncing to computers requires Internet connection and USB port
  • Syncing to mobile devices requires Bluetooth and Internet connection
  • Syncs with Windows Vista and later, Mac OS X 10.6 and up, iPhone 4S and later, iPad 3 gen. and later, and leading Android and Windows devices

Initial Device Impressions

There are many colour variants of the band that you can get at the time of purchase, but there are also first and third party aftermarket wristbands available for the Fitbit Flex. The colour of this band is slate. The other nine out of ten available colours are black, Violet, Lime, Pink, Navy, Tangerine, Teal, Red and Blue.

Underneath the rubber wristband is where the removable sensor is placed through a ‘window’. There are five LED dots to indicate a certain activity achievement or mode (such as activating sleep mode). Due to its width, It looks simply like wearing a rubber band bracelet rather than a watch.

Compatibility and Initial Setup Impressions

Fitbit Compatibility

The device requires access via Bluetooth to create a sync between the wireless tracker and the smartphone. The setup is tested with three phones- An old Sony Xperia L, Sony Xperia Z3 Compact and Coolpad Note 3, which was also reviewed. The device synced with Z3 Compact and Coolpad Note 3. Fitbit does have a list of compatible devices for Apple, Android and Windows devices, whose app is also available via its respective app stores. In its Android compatibility list, it did mention Z3 Compact, but the Coolpad Note 3 is not mentioned.

I think it would be best if the app had some way to update its list if an unknown device has successfully synced, or to notify Fitbit provided the user gives permission to the app. Considering there are countless Android smartphones and other devices, this is one of the ways to have a larger and more accurate compatibility list. Similarly, there should be a way to also report incompatibility so that Fitbit can check and provide the relevant updates whenever possible.

With the Z3 Compact and the Coolpad Note 3, the installation and sync process is very user-friendly. It does remind you of the essentials you will be using and what you should do every step of the way. You don’t need an instruction manual. The app guides you all the way.

The app does not have other language options. Note that a single app is made for all of its devices whose settings and information reflect accordingly. Maybe Fitbit could provide other international language options by providing an option to download the relevant language pack during setup.

Wristband and App Interface

There’s no screen, but it does have LED indicators present on the wireless sync dongle. The LEDs can be seen through the rubber band thanks to a tinted window. You need to tap on the band to indicate a certain level of activity achievement or notify the device that you will be doing a particular activity- exercise or sleep. There are other GoFlex variants with a screen, but LED indicators help in having a minimal design. Not everyone would like to wear a wireless tracker that also functions as a watch.

Each LED indicates 20% of your activity that you achieve on the daily basis. Minimalistic function at its best.

The device will require you to create an account to keep the tracking and logs active. Only one wireless sync device can be used at a time per app, but you can have more than one Android devices to monitor your activity from the same account. This way, somebody else can keep a track on your activity as well, should you require and choose to do so. However, it will require that device to be in sync as well. The desktop app does work just the same, but I haven’t received the wireless dongle for the PC with this review unit. This is good, especially for those who are concerned about your activity and want to make sure you’re not being lazy (or tracking how lazy can you get).

The main Android app interface has all the relevant information you require from this device. The Fitbit Flex registers and logs the following activity:

  • Steps
  • Distance
  • Active Minutes
  • Exercise (Run/Walk/Hide)
  • Weight
  • Sleep Log
  • Food Log
  • Water Consumption Log
  • Calories Burned

Fitbit app’s options have more customization settings:

The app also has challenges and badges to keep its users more engaged and interact with the device, therefore encouraging its users to some extent to complete certain activities and challenges.

You can set your country, along with the units of measurement. Another best feature is the hidden alarm, which vibrates the devices once it hits the timing. You can also set multiple alarms, and set repeat settings for all days or preselected day. The app requires to have a Bluetooth enabled to sync the new alarm setting, but the Android device doesn’t require to be in the range of the device (or with Bluetooth-enabled) for the wireless tracker to vibrate. This is good, as it enables the user to deactivate the device’s Bluetooth after syncing the tracker’s logs and/or the silent alarm.

The steps, distance, active minutes and calories are logged automatically. Sleep is logged by tapping the device (two LED on and fading away). Water Consumption needs to be added manually via the device which has its app installed.

Once a week has passed, the app combines each activity’s daily log and combines it into a weekly log once the week is completed. You can still open up older day logs as well by pressing the particular date of the week. All the logs are maintained up to 30 days by the app.

The sleep log shows ‘Sleep Pattern’ between Asleep, Restless and Awake. You can add your sleep timings manually in case you have forgotten to tap your wireless tracker before sleeping, but it will now show sleep pattern “Restless” and “Awake”. The wireless tracker keeps a track of your sleep when there’s a body contact.

Exercise tracker has three settings- Run, Walk, and Hike. Exercise needs to activate manually while the user needs to select from one out three exercise options. Via GPS, it will keep a track on your activity and log the number of kilometers covered and its timeframe.

Food Logging has a barcode scanner which uses your Smartphone’s camera (and can also allow the user to use the inbuilt flash), but in order for the nutritional value to reflect on the barcode scanner, its details need to be there with Fitbit. It does let its user know that you can add the food item to its database by taking photos, but it doesn’t seem to be having that function to do so.

You can add “Custom Food” but you will require to manually add in every detail, including the food’s nutritional facts and serving size.

When you meet a certain a certain challenge, earn a badge or have a low battery life, Fitbit sends an email to the registered email address.

Device Compatibility

Fitbit’s compatibility range is something that many users will appreciate. It is compatible with a range of Android, iOS and Windows devices. You can connect this to your PC and it comes with a wireless dongle.

Fitbit flex 14

Single Charge Lifespan

A full charge lasts between six-to-seven days, that is one-to-two days more than what Fitbit advertises about Flex’s battery life. But I would really appreciate if the app indicated the percentage of charge, rather than having options varying “Battery Full” to “Battery Empty” mode. Even with Battery Empty mode, the LED indicators on the device did have some power for a good few hours.

Wear and Tear

The operating temperature of this device is between -20°c to 45° c. The tracker doesn’t become warm during use or heavy activity, nor the band is uncomfortable in the long run and cause irritation. Fitbit doesn’t recommend secure the band on your wrist tightly. Even if the band does become wet due to water or sweat, the underneath area doesn’t cause any skin irritation. at least in my case. Should you choose to clean the band, Fitbit recommends using a gentle soap-free cleanser. I use isopropyl alcohol with 70% alcohol content since it evaporates once it touches the surface and it’s a good disinfectant. Though you can wear it during shower it’s best to keep it away from soap.

The band does have a good level of protection against sweat, rain and splash, but I would recommend cleaning the wristband, the tracker and the band’s underbelly area with a dry cloth once a day. Fitbit also recommends keeping your skin dry and clean.

Fitbit also says that removable clasp is a surgical-grade stainless steel.


It’s a good wireless band. Calling it a basic one wouldn’t be accurate as it does give an easy-to-use access while retaining minimalistic design to maintain a ‘low-profile’ look around your wrist. But it still offers a lot more than just keeping a track of your steps, distance and the amount of water you can drink. The battery life is great though I wish the app can mention the remaining battery life percentage wise. A single charge will last you a week. Fitbit should have a report or add unknown device option so that its list of compatible devices can be crowdsourced or add support for incompatible devices, provided it’s well within the device hardware requirements.

One feature that will be appreciated in such a form factor is the heartbeat monitor, but that’s where Fitbit Charge HR comes in.

I just find it weird that Sony Xperia L wasn’t syncing with the tracker via the app, even though the smartphone can identify the tracker via its Bluetooth tracker. Both devices are Bluetooth 4.0, and Xperia L has all the latest update with Android 4.2.2. Coolpad Note 3 is running on Android 5.1 and the Z3 Compact is running on Android at the time of testing. This was tested with Fitbit app 2.13 with Flex firmware version 7.64. During the time of testing, the app was updated a few times so its good to see that Fitbit is rolling out updates at regular intervals.

If you are starting with a wireless band for the first time and need something that’s easy to use. Fitbit Flex is one of the wireless trackers you will like to shortlist, assuming it’s there in the compatibility list.

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