Flex 3

The FitBit Flex is a wireless waterproof wristband that syncs with both iPhone and Android phones and tablets. It tracks and estimates your daily steps, distance walked, calories burned and at night it monitors activity levels to track your sleep cycle. It also has a built-in silent alarm that vibrates when it goes off.

Range of different coloured FitBit Flex wristbands

I have worn mine for 5 months and it has provided me with some very useful information about my lifestyle and in conjunction with my symptom diary it has helped me gain more accurate information about how my health affects my activity levels and sleep quality. However, it does only measure activity at wrist level and to gain a good estimate, allowances have to made and taken into account.


  • Size:  Small (5.5 – 6.9 inches/140 – 176 mm), Large (6.3 – 8.2 inches/161 – 209 mm), Width: 0.6 inches (13.99 mm)
  • Colour: Black, Slate, Tangerine, Teal, Navy, Violet, Blue, Lime, Pink, Red
  • Operating System: Wireless sync to PC and Mac (with a USB dongle), Android, iOS and Windows Phone. A list of compatible devices is here.
  • Memory: It has a built-in memory, but it is important to regularly sync. It tracks detailed data for 7 days and daily totals and summaries for the past 30 days.
  • Display: Five white LED lights used for goal tracking and battery usage
  • Connectivity: Wireless bluetooth and USB dongle for PC and Mac
  • Bluetooth: Bluetooth 4.0
  • NFC (Near Field Communication): Enabled
  • Battery: Lithium-polymer battery with a 5 day batter life when fully charged

For full details on the specs, have a look at the specs listed on the official site.

FitBit Flex wristband from different positions

The Flex Wristband

The wristband is designed to be worn 24 hours a day and it is pretty comfortable to wear on either arm. The clasp requires some precision and strength to secure and this is causing me some issues because I remove the FitBit flex when I am sitting down for longer periods, but for anyone who will only be removing it to charge, which is about every 5 days or so, that should not be a problem.

Skin allergies

The official site states: “Our Flex wristband is made of a flexible, durable elastomer material similar to that used in many sports watches. It does not contain latex. The clasp is made of surgical-grade stainless steel and contains traces of nickel.” For those with a nickel allergy, although surgical-grade stainless does contain traces of nickel, it is so tightly bound that it usually does not cause an allergic reaction.



The FitBit tracks the movement of your wrist and as a result, it isn’t as easy as put it on and read the numbers to measure your activity levels accurately. Any wrist movement counts as steps, even when you are not walking. Activities like computer work (mouse usage in particular), gardening, manual wheelchair propelling and cooking all added counts toward the daily steps even carried whilst sitting down. Conversely, unless your wrist was moving whilst you are walking, steps did not count. When pushing a trolley in the supermarket or a buggy, using a walker or crutches all reduced the count below the number of steps actually taken. I also have shoulder and wrist issues and when either is in significant pain I do not move my arm when walking and this too meant that steps were not recorded.

Some of these inaccuracies can be mitigated. Just take the FitBit off when carrying out certain activities, although I do wish there was a pause button on the App. Others, particularly for anyone with health issues, are not as easy to account for. It isn’t possible to start swinging in injured wrist around all day every day or for those with small children, to push a buggy with one hand the whole time when walking.

I still receive some useful data from my FitBit on the very small scale and the very large scale. I do some walking regularly as part of my physiotherapy and when I check the figures before I start and immediately after, it does give me a reliable figure to compare from one session to the next. I also find it useful to compare activity levels on a more general scale where some inaccuracies is not that important to my symptom diary in particular to see what impact different symptoms have on how active I am.

daily steps graph from FitBit

Sleep tracking

Sleep tracking is also done by measuring the activity of your wrist. For those of us with insomnia and sleep issues, this creates some issues. I spend a lot of time during the night listening to an audio book or reading, both activities does not involve using my wrist and so my FitBit records me as being fast asleep when in fact I am wide awake. I get around this by making a quick note when I am awake and adding that to the data collecting, unfortunately, this is not a function that is part of the software, so whenever I want to make use of the FitBit data, I have to do so with a spreadsheet next to it.

Despite these flaws, I still find the sleep tracker invaluable. It is very difficult to try and keep track of how much I sleep, particularly as it often feels as if I have slept much less or much more than I actually did. The FitBit also tracks how often I get out of bed and move around very accurately, so that I have an exact figure of how many times I have gotten out of bed during the night. As long as I adjust the data on a separate spreadsheet to allow for night time reading, it gives me the clearest picture I have ever had of how much sleep I am getting.

It is unfortunate that it has to be manually triggered at night and when waking up. I use my phone to play audio books during the night, so the FitBit flex screen is not on my phone when I wake up in the morning and I tend to forget to turn off the sleep tracker. It would have been great if the sleep tracker automatically detected activity levels over a longer period and turned off the sleep tracker using that data.

FitBit sleep log

Other data

The FitBit flex calculates calories burned based on activity levels and other activities, weight, foods and water consumed can be added manually through the App.


Visual Accessibility

The FitBit flex has 5 small LED lights on the wrist band that will flash when battery power is low or when the device is tapped, but both of these are optional extras and the software will display this information as well. I did not come across any constraints for anyone with visual symptoms like photophobia, visual impairments or for blind users or any potential triggers for either migraine, motion sickness or seizures. I have not tested the application for blind users myself, but blind users on-line does review it as accessible on both iOS and Android.

Audio & Speech

It does not make use of any audio and as such should be accessible for anyone with a hearing impairment, a hypersensitivity to sound, deaf users or a speech impairment. In fact, as someone who experiences audio hypersensitivity regularly, one of its most useful features is the silent vibrate alarm that can be set to any time of the day.

Input and Touch

The wristband itself requires no input. Those with restricted hand or upper body use may need some help securing the device on the wrist, but other than that, it is fully controlled through software that runs on a variety of operating systems, including mobile devices, PCs and Mac.

Ease of Use

The device is not particularly complicated to set-up or sync to a device in order to access the software, but the ability to follow multi-step instructions is needed and anyone with a significant learning disability may need some help to set it up. Once up and running, it is well designed application that display data in a logical manner that is easy to use, but it is an product that is about data and although there are graphs as well as figures, users need to have basic literacy skills and an understanding of basic math to be able to interpret the data.

Data is displayed in relation to a goal set by the user and these are colour coded, so it is possible once someone else has set it up to be able to use the device to achieve particular activity levels without the need to review the data. For example, to use it to reach a particular set step count already programmed, all the user has to be able to do is tap the wristband and count the number of lights. There are 5 lights and each count 20% towards the goal and once a goal is reached, the wristband vibrates.

On the application, data is colour coded in yellow, orange and green to denote progress (colour is never used as the only indicator, so the application is easy to use regardless of any colour blindness), and on the graphs when goals are met data is displayed in green and when not in grey.

Red FitBit worn on wrist whilst holding chop sticks

Product Information

Price: RRP £79.99
Retailer: Amazon:£68.15 (black) – £106.66£106.66 (blue) (depending on colour)

Included In The Box

  • 1 x Fitbit Flex Tracker
  • 1 x Small wristband
  • 1 x Large wristband
  • 1 x Charging cable
  • 1 x Wireless USB dongle
  • 1 x Free Fitbit account


The FitBit Flex is a durable, comfortable, stylish wristband with many desirable features that looks perfect for the average person carrying out daily activities and exercise in a normal fashion. It is accessible for blind and deaf users as well as anyone with any other visual or hearing impairment, including hypersensitivity, but it is less useful for anyone with physical issues that change the way every day activities are carried out. If you don’t move your arm when walking, for example pushing a supermarket trolley, walker or pushchair, or move your arm a lot when not walking, like with heavy mouse usage, gardening or cooking, data is going to be inaccurate.

Most of the inaccuracy is less relevant if you are just comparing your statistics to your own statistics as most people follow a general daily routine so that tasks like cooking regular meals will have the same every day and skew all data to roughly the same extent, but for those of us with variable conditions with variable daily routines, these inaccuracies can make quite a dent in the reliability of the data.

Woman wearing FitBit whilst carrying lunch box and walking up concrete steps

Despite its flaws, I still find the FitBit very useful. It tracks how often I get up at night very accurately, in conjunction with my own notes, I can still get a pretty clear estimate on how much I sleep (I log other sedentary activities at night and subtract those from the total sleep figure my FitBit tracked) and as long as I remove my FitBit when doing activities that involve a lot of wrist movement and add on walks where I made use of an assistive device that immobilized my wrist, the data is still accurate enough for me to get a better picture of how well I sleep and how active I am than I have without it.

The silent alarm is its most coveted feature as I can set it to reminders at specific times so that I don’t forget meal times, important appointments or when to take my medication and it wakes me up without any noise or vibration under my head (like other silent alarm clocks I have tried in the past).

I have not been particularly excited or interested in wearable technology, but I like my FitBit flex, I make use of it every day and the data it collects does help me manage my health, prompts me to be more active particularly on bad days and keeps me on track without the need to be near my phone. Its limitations as only a fitness bands is becoming frustrating and I wish the software had additional features that would allow me to interact with my data and adjust it to suit and reflect my life, ability and lifestyle.

If it was cheaper, I would highly recommend it to everyone, but with its pricetag at around £80, I would recommend that anyone with a physical disability or highly variable condition think about how accurate and useful it would be in their case. Does your wrist move with your feet and does your feet rest with your wrist? If the answer is yes, the FitBit is a great asset to track your activity levels, sleep quality and quantity every day.

FitBit Flex was released in May 2013. The review is based on the black FitBit flex purchased from FitBit via Amazon. *I made use of a Personal Assistant to test some of the features due to restricted mobility.


  1. sgallo 05/01/2016 at 2:31 am - Reply

    I have a seizure disorder and have worn the flex for 72 hrs. During my 3rd night I woke 28 tomes with partial seizures. It did not occur to me that the led lights and sensitivity could be causing the seizures.

  2. nrcountryman 04/10/2015 at 4:20 am - Reply

    I am in a manual wheelchair and would like something that counts my movements.

    • Chris Ellis 04/10/2015 at 7:29 am Reply

      Unfortunately the fitbit might not be the best choice. The Flex works by measuring your arm moving back and forth which you do on a manual wheelchair but you don’t do it consistently. There isn’t a great answer to this. The best solution we’ve found so far is using something with GPS built in that tracks your position rather than your movement. This could be an app on your phone or a watch like the Garmin 225 but they have disadvantages – they eat battery power and don’t work reliably indoors.
      The newer generation of trackers seems to be taking a hybrid approach of motion and position tracking and these potentially solve the problem but I’ve not seen one yet that’s got it quite right. The Microsoft Band 2 that is due to be announced on Tuesday may well be worth a look.

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