Fitbit Flex Fitness Tracker - Slate

  • Model #: FB401SL-CAN
  • Web Code: 10252520
  • Release Date: 06-17-2013
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Fitbit Flex is the slim and discreet activity monitor that never sleeps. All day, this wristband tracks your steps, distance, and calories burned. At night, it monitors your sleep cycles and quality of rest. Flex syncs the data to your computer or smartphone so you can visualize, track, and share your progress.

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You jolt out of bed, your jarring alarm blaring repeatedly in the background. As you squint at the sun streaming through your window, you silently berate yourself: these long, dragging days have got to stop. It's time to explore beyond the well-trodden path of work and home, and make an appointment with fitness. It's time for the Fitbit Flex.

Not sure where to start? Wear the slim and comfy Flex activity tracker all day and night and, literally, just forget about it until you need to recharge.

Your plate's full? Flex keeps track even when you're sleeping so you can get the push you need to reach your health goals. See how Flex can be your gentle yet persuasive digital motivator.

Why you need this:

  • Just like a pedometer, but loads better: The activity tracker records your steps, and distance travelled, and calculates the calories you burned throughout the day.
  • The activity tracker that never sleeps: At night, Flex automatically tracks your sleep cycles, reading how often you wake up in the night, and measuring and rating your quality of sleep. Set your desired time and your Flex wakes you up with a silent alarm so as not to wake up your partner.
  • Your personal coach for all things fitness and health: Fitbit's food database helps track your food and water intake, and will let you know when you've met your daily calorie objectives. On-board LEDs light up as you get closer to achieving either your step, distance, or calorie goal -- it's your choice. What's more, Fitbit is compatible with a slew of lifestyle apps so you can see the big picture.
  • Learn to eat, live, and sleep better: The Fitbit app and online dashboard display a real-time snapshot of your movement, showing you easy-to-read graphs, charts, and tools that make sense whether you're a rookie or a pro. Share your progress with family and friends, compete with fitness buddies on the leaderboard, and earn badges for fitness milestones.
  • Expands your digital world: Flex syncs wirelessly and automatically with your compatible device via Bluetooth 4.0 technology, be it your enabled smartphone, tablet, or computer, so that you can view your custom dashboard online or while on the move through the Fitbit app.
  • A trusty companion: Flex resists sweat and water splashes so you don't have to hold back on training when the weather is less than ideal. The rechargeable battery lasts upt to 5 days on a single charge so you can indulge on a long weekend getaway without losing sight of your fitness goals.
  • Small and discreet: Wear this wristband without cramping your style, and show your personality with one of Fitbit's accessory bands (sold separately).

*Battery life and charge cycles vary with use, settings, and other factors; actual results will vary.

What's in the Box?

  • Flex Tracker
  • Small and Large Wristbands
  • Charging Cable
  • Wireless Sync Dongle

Manufacturer's Warranty:

  • Parts - 1 Year(s)

Geek Squad Protection

We fix it or replace it.

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  • Display
  • Display Technology
  • Display Colour
  • Touchscreen
  • Illuminated Display
  • Attachment Location
  • Connectivity
  • Bluetooth
    Bluetooth 4.0
  • Wi-Fi
    Not Applicable
  • USB (Data)
  • NFC Enabled
  • 3G
  • 4G LTE
  • Smart Phone Synchronization
  • Data Syncing
  • Wireless Syncing
  • Memory Card Type
  • Activity Monitoring Features
  • Goal Setting
  • Real Time Data Syncing
  • Calories Tracking
  • Distance Tracking
  • Steps Tracking
  • Running Tracking
  • Elevation Tracking
  • Climbing Tracking
  • Sleep Tracking
  • Food and Drink Tracking
  • Notifications & Controls
  • Incoming Calls
  • Missed Calls
  • Answering Calls
  • Smart Phone Battery Alert
  • Music Controls
  • Camera Control
  • Find My Phone
  • Voice Commands
  • Email
  • Calendar
  • SMS
  • Facebook
  • Twitter
  • Instagram
  • Google+
  • Weather
  • Silent Alarm
  • Vibration
  • Illuminated Alerts
  • Sensors
  • Number Of Sensors
  • Gesture/Motion Control
  • UV Index Monitor
  • Accelerometer
  • Ambient Light Sensor
  • Compass
  • Altimeter
  • Body Temperature
  • Ambient Temperature
  • Barometer
  • GPS
  • Perspiration
  • Heart Rate
  • Compatibility
  • Web-based Application
  • Mac iOS Compatibility
    Yes - See for a complete listing
  • Android Compatibility
    Yes - See for a complete listing
  • BlackBerry Compatibility
  • Windows Phone Compatibility
    Yes - See for a complete listing
  • Mac OS X Compatibility
    Yes - See for a complete listing
  • Windows PC Compatibility
    Yes - See for a complete listing
  • Companion App Required
  • Software/Apps
  • Compatible App Stores
    App Store; Google Play; Windows Store
  • Approximate Number of Apps Available
  • Power
  • Power Type
    Battery Powered
  • Battery Type
    Rechargable Lithium-ion
  • Battery Life (Typical)
    5 d
  • Charging Time
    1 - 2 h
  • Charging Method
  • Other Features
  • Classification
  • Alarm
  • Designed for Sports & Fitness
  • Camera Resolution (Still)
    0 MP
  • Camera Resolution (Video)
    Not Applicable
  • Built-in Speaker
  • Built-in Mic
  • Water Resistance
    10 m; Sweat Resistance; Rain Resistance; Splash Resistance
  • Dust Proof
  • Number of Physical Buttons
  • Eco-friendly
  • Physical Features
  • Band Material
    Plastic; Surgical Grade Nickel
  • Band Colour
  • Band Size
    Not Applicable
  • Minimum Band Size (Circumference)
    140 mm
  • Maximum Band Size (Circumference)
    240 mm
  • Adjustable Band
  • Removable Band
  • Clasp Type
  • Width
    1.4 cm
  • Height
    24 cm
  • Depth
    0.6 cm
  • Weight
    80 g
  • Warranty Parts
    1 Year(s)



Customer Reviews

3.3 / 5
Based on 32 review(s) More about Customer Reviews

Ratings in Detail

  • 5
  • 4
  • 3
  • 2
  • 1

Positive vs. Critical Reviews

Positive 81%

26 Reviews

Critical 18%

6 Reviews

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  • from Burlington, ON

Just Okay

I bought this FitBit during the Boxing Day sale December 2014. It works okay, sometimes. It does not always record the steps or active times and the battery warning level gives you only about an hour before it dies. The band has already ripped almost all the way through at the display. It is obviously a known weak point because FitBit has replacements for sale already on the market. I don't think I would recommend this product to anyone but if they asked, I would definitely warn them of the problems I have experienced.

  • from Hamilton, ON

Died In A Year

I bought my Flex in July 2014. The charger was dead in 5 months. I had to buy a new one. In July 2015, the Fitbit itself totally went on the fritz. I tried to reset it w/o success, and I emailed the support line and haven't received a response in 5 days. Not very pleased, because I imagine that I'll have to send it away, and they'll probably send me a new one...but this is likely going to take until September. Save your money and buy a different one.

  • from Sudbury, ON

Fitbit Flex

It is very motivating to get in my steps each day. I like the food tracking and the sleep tracking....on line help was not as helpful as I would have liked. Lots of trial and error.

  • from Windsor, ON


Steps and sleep did not get recorded. Rebooted per online instructions. Didn't help. [...] Replaced it with Fitbit one which works great and records everything accurately

  • from Collingwood, ON

Fairly Useful

Have had many issues syncing. FitBit help is semi-useless. Trial and error is best. So when it doesn't sync, information/feedback is sporadic. When it does work, it motivates and encourages to get your steps in. Would I buy another, likely no.

  • from Toronto, ON


Decent at tracking steps. My unit won't go into sleep mode despite trouble-shooting this issue. No big deal- I just make a mental note of bedtime and awaken time and manually log it in the next day. Unit definitely motivates a reasonable activity level, particularly on lazy days.

  • from Montreal, QC

Couldn't hold a charge after 6 days

Useless. Charged it up once and then the battery drained down and lasted 6 hours and then the second charge it lasted 2 hours.

  • from Fort Mcmurray, AB

great product

It was a great product.

  • from Montréal, QC

Gave Me a Rash

My christmas morning was ruined by the fact that I had a bad skin reaction to the fitbit flex I received as a gift Christmas Eve. I have no allergies (I have been tested) and clearly there is something wrong with the product. I slept all night the 24th wearing the bracelet, and I woke up in the morning with my arm covered in red itchy bumps. When my boyfriend, who bought the gift called fitbit the response he got was that he should mail the band back in for a refund. I find this insufficient customer service for the situation. Not only would it take less time for him to receive a refund from the store he purchased it from, Fitibit, as the company which produces and manufactures the product should offer more than a simple refund as acknowledgment of the error. As both a student of business, and a consumer I am appalled at how Fitbit customer service offered the bare minimum to a complaint such as this. Such little consumer consideration is unacceptable.

  • from Toronto, ON

So Far So Good!

I love my FitBit.... That being said, I find the food list to be mostly American food and most of it to be restaurant or pre-packaged food. It's difficult to find listings for homemade food. I would like a more concise and comprehensive user guide (on-line is fine). There are some applications that I still have not been able to figure out how to use. I am in competition with my niece and we are both pushing really hard for 15,000 steps a day and this is just week two for me. My charger does not work. I have contacted the company and the process is slow, however, it is Christmas and I have to be understanding. I've been borrowing other people's chargers and have made do. I have heard from others that the company is excellent to deal with and that they will replace the charger.

  • from Winnipeg, MB

Decent unit, but battery life could be better..

Got this device last Christmas, and overall works great. My only issue is the battery life could be better.. Only get 5-7 days before a recharge is needed. That requires taking the dongle out of the band and recharging for a few hours. Not a big deal, but doing this on a weekly basis puts pressure on the rubber casing which has now cracked after only a few months of use. Was hoping for a longer life than that. Will likely require a replacement within a few months.

  • from Edmonton, AB


I bought it couple of months ago to have a consistent measure of my physical activities and no regrets! Knowing what I am at every day, keeps me motivated to do an extra effort to reach my daily goal. I'd recommend it. Works fine with Iphone, can not say the same with Android.

  • from Toronto, ON

Less than 2 months and it's dead

Purchased mid July and it's already dead. Extremely difficult to charge over the last few days and when charged the charge doesn't hold. Completely disappointed. Waste of money.

  • from Milton, ON

Great but ......

I love my fitbit. My biggest issue is that since December I have replaced one and now my second one is dead and needs replacing. Having said that fitbit customer service was fantastic.

  • from Vineland, ON

Fitbit Flex Wireless

Outstanding. I'm a senior that needs motivation to keep moving as I'm well aware of the discomfort of not moving enough. I love everything about the flex .... I don't need to follow my calories but most of the other functions are great and will come in handy when visiting my family doctor.

  • from Nelson, BC

Great motivation

Simple to use, great motivation to keep moving. App could used some improvements but they're already working on that.

  • from Montreal, QC

great FitBit

love it, easy to use. I have not used all the functions yet but will be doing so as time goes on.

  • from Dundas, ON

Love it

I love the accessibility of the wireless app on my Samsung phone: I can check my status and add food items throughout the day. I had no problem setting it up on the computer and it is so easy to use. I love it.

  • from Saskatchewan

Good tool

Tool is easy to use and a helpful motivator

  • from Ottawa, ON

An excellent tool

I purchased this for my wife and received it about a week ago. She has been using it constantly as a tool to balance her consumption of water, to stop making generalizations about her level of activity, and to really get a handle on her overall fitness. It does everything it says, and my wife has been very impressed with it. Her only complaint is that she has to force it to synchronize with her app with her PC more than she would like as it doesn't always want to do it automatically like it's supposed to. I would buy one for myself, but the lack of a heart-rate monitor is a deal-breaker at this price.

  • from Kitchener, ON

Why did I wait so long?

love it....simple to use. I'm not a super athlete or a high tec person but do enjoy the gadget aspect. It does make me walk more and that is a good thing. Also find the sleep tracker interesting. Now if spring would just get here I could get outside to even walk more

  • from Toronto, ON

Pentimento Fitness Accessory

Essentially, for those who don't want to read too much into this review, I will break it down for you in bullet point: - Waterproof, Sweat Proof, Durable and I have only replaced the bracelet (The rubber exterior. not the bit itself) once since I bought it back on July 17th 2013. The replacement was purchased two weeks ago. - Stylish, not really noticeable, comfortable and no rash from the silicone band like other Fitness tackers or the pebble watch. - Battery life is sufficient and with the most recent update, it syncs directly to your iPhone and Android powered devices, instead of just the laptop with the dongle. - Very integrated with the website and application support. My fitness pal works like a charm, but personally all I need is the site for my purposes. It's a must buy and now I have a total of four alternative bands to go for my every day look. For $[...] it's a steal against it's competitors. I have yet to try the Fitbit Force. Stay tuned :) Cheers

  • from Ontario

Fitbit Flex

Was what I expected. It is easy to use and comfortable- I forget I have it on. Step count seems to be fairly accurate. I was surprised that a brisk walk counts as very active as I only consider it moderate but other than that it's worked as I expect. The sleep function has helped me identify and eliminate triggers to poor sleep and also to identify things that contribute to a better sleep.

  • from Gatineau, QC

Just what I expected

I researched this quite a bit before I bought it. It is exactly what I expected and a little bit more. The technology is very cool. It has actually made me take the stairs, take a walk or hit the treadmill on occasion just to push myself past the 10,000 step mark. I have also enjoyed the sleep tracking and even had my wife wear it a few times just to understand how we sleep. My only real regret is not forking out a few more dollars for the Force. The FitBit company certainly seems to have their act together.

  • from Kitchener, ON

came off and lost

Go waste your money on something else. A week after wearing it the strap came off and I lost it somewhere. I wasn't doing anything physical in the afternoon this happened.

  • from Windsor, ON

Fitbit flex helps me flex!

Great product! I have had a few hiccups with the app itself but not the flex. It is sensitive to movement so if you are riding a bike on a dirt track your flex might vibrate into sleep mode. Overall, it keeps you in check and motivated. I love the fact that I can sync my fitness pal app with it. Fantastic!

  • from Torbay, NL

Pretty straightforward, misses a few features

I used to have the fitbit clip on version but lost it on a run so was looking for a version that would not disappear. This does everything I want, including tracking my sleep and syncing to my fitness pal which I use to track food and connect with the other people on my fitness program. The only things i miss? It only syncs to my iphone, not my ipad, and my old fitbit was big enough to have messages on the screen which was a nice touch. That said, i love that I never have to take it off, it has survived regular wear and vacation time and I would recommend it.

  • from Vancouver, BC

Two Month Review of FitBit Flex

I've had the FitBit Flex for 2 months now and I really enjoy it. Although already active, it does motivate me to keep moving. The battery life has been longer than expected, although it has died on me a couple times as there is no battery level indicator on the product: one must log in to be notified to charge the battery. Issues: this product does not link wirelessly to my Galaxy 2 LTE phone. Although I can view my data on my phone via the FitBit app, I must first download it to my laptop. The most recent issue, and the one prompting this review, is that after 2 months the bracelet is already starting to fall apart. I wear the bracelet 24/7, although I remove it for showering and dressy occasions. The glue attaching the bracelet to the light indicator window has started to separate - perhaps this product is not as sweat-proof as indicated. Replacement bracelets are available, but not through Best Buy.

  • from Winnipeg, MB

A great motivator

Tied into the Fitbit app on your smartphone, the fitbit flex is a great device for tracking your activity, and sleep. Although it wont make you fit, or lose weight for you, it is a great tool to see just how active or inactive you are on a daily basis. The feedback of your current activity level, as well as seeing how active your friends are really helps to get you motivated. Although I often have trouble telling my device that I am going to sleep, overall the Flex is easy to use and I highly recommend it!

  • from Toronto, ON

Changed my life

My fitbit amazing! I absolutely love it. I also bought the scale that goes along with it. I have lost 5 lbs since using it and am so much more health conscious than I used to be.

  • from Ajax, ON

Fitbit Flex is good but not great

The Fitbit Flex is a cool piece of technology to track your activity level. However mine failed after a week (would not respond to tapping or charging). I left it on my desk for a couple of days and then tried charging it again. It came back to life and has been working for the past week. Not sure why it stopped suddenly as I had recharged it 3 days prior. Will see if it happens again. As for the tracking it seems to do a decent job. It exaggerates a bit but that is to be expected. From what I have read, all bracelet devices do to some extent. I am told the clip on units do a better job but the bracelet works better for me.

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