Fitbit Flex Wireless Activity and Sleep Wristband

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Wearable personal trainer.

The Fitbit Flex Activity Tracker acts like your own personal wearable trainer you always can carry around. It measures your activity level at daytime and monitors your sleep quality at night. That is something a real personal trainer wouldn’t do.

Update 2018: Check out the cool Fitbit Ionic.

The wristband is supposed to be worn 24 hours a day and is targeted towards both beginners and experienced fitness people that want to maintain their shape and health. Fitness wristbands have really become popular this year and motivated people to walk or run just a little further.

Previous post: EatSmart Precision Digital Bathroom Scale


The activity tracker wristband is made by a company called Fitbit based in San Francisco. They have several other wearable activity trackers in their portfolio like the Fitbit Zip clip and Fitbit One. The Flex was launched in 2013 

They have received many awards for their products including the ‘CNET Best of CES 2013 Award Winner’ and the products have many fans that love the intuitive design and simple functionality.

Fitbit Flex Wireless Activity and Sleep Wristband

Fitbit Flex Wireless Activity and Sleep Wristband

How Fitbit Flex works

The tracker itself is a small removable piece you put inside the rubber band. You attach the gadget to your wrist and then it starts to log your activity. It measures your steps, distance, how many calories you have burned and how many minutes you’ve been active. The sleep monitoring keeps track of the quality and how many hours of sleep you had.

All this info is synchronized via USB to your free Fitbit account or via Bluetooth to the free smartphone app and you have all the statistics in your hand. You can make diagrams and add stuff like what you eat, your weight goals, blood pressure, and heart rate.

You are supposed to wear the wristband 24 hours. It can even wake you up, and only you, with a silent vibrating alarm. That is pretty neat.

5 small LED lights show the daily progress. You decide your daily goal in advance and each light illuminates when you have reached 20% of that goal. So if you miss a light you know what to do. When you reach your daily goal the Flex vibrates to let you know.

The wristband comes in two sizes: Small 140-176 mm and Large 161-209 mm. Both follow in the box.

Software and Apps

On a PC you download and install the Fitbit Connect software and make a free account. You use the accompanied USB dongle to synchronize to your PC.

On smartphone and tablet, you download the free Fitbit App for either Android or iPhone/iPad/iPod. All the data is synchronized via wireless Bluetooth. You can track your progress and compete with others.

Click here to read more about the benefits with activity trackers.


In addition to show you your training progress the LED lights also give you feedback on the battery level. The battery lasts for between 5 to 7 days before you need to recharge it with a USB connection. It takes between 1 to 2 hours to charge.


  • Slim, light and easy to wear
  • Tracks distance, calories burnt, activity length and sleep
  • Rechargeable battery that lasts for 5-7 days.
  • 5 LED lights for indication of battery and daily goals
  • Memory for 30 days (7 days detailed)
  • Waterproof down to 10 m
  • Warranty 2 years
  • Two sizes – Small or large
  • Weighs only 8,5 g
  • 10 colors to choose from
Fitbit Flex colors

Which of the 10 colors do you prefer?

What’s In The Box?

  • Fitbit Flex tracker
  • Small and Large wristband
  • USB wireless sync dongle
  • Charging cable
  • Free Fitbit account
  • Access to Apps
Fitbit Flex Wireless Activity and Sleep Wristband Box content

What’s in the Fitbit Flex box

My Opinion

A great entry-level activity tracker for a reasonable price with most of the functions you need. Perfect if you need to have a waterproof activity tracker for swimming and running in the rain.

 Pros +  Cons –
  • Two Sizes
  • Tracks what you need
  • Charge quickly
  • Stylish colors
  • Waterproof
  • Sleep monitoring
  • Bluetooth Wireless synchronization
  • Cheap compared to many competitors
  • Can register wrong steps since you have it on your arm
  • Lacks visual feedback (but have nice LEDs)
  • No stair step count
Click here to read about the Fitbit Zip.

Where Can I Buy Fitbit Flex?

Buy it through the Fitbit Store and get Free Shipping.

Purchase Product

US: Purchase on$74.89.

Purchase Product

UK: Purchase on

If you are in or close to the USA click the top link to check recent price and additional info. If you are in or close to the United Kingdom, click the bottom link.

More Info or Questions

If you want more info before buying, check out the Fitbit Flex reviews from other users here.

Do you have any questions or comments on my Fitbit Flex review, do not hesitate to send me an e-mail on andreas (at) or leave me a comment below.


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