The Fitbit Flex offers the same wireless syncing, compatibility with a wide range of devices and connection to Fitbit's web account as the brand's other leading activity trackers. By replacing the display with a series of LED lights and losing the stair-tracking altimeter, Fitbit keeps the price at $100, making the Flex one of the least expensive top-rated devices. Users have the opportunity to tailor the look of their Flex with a variety of available accessories.
Basic fitness tracking. The Fitbit Flex tracks steps, overall distance, number of minutes spent doing cardio-type activities and calories burned. A sleek LED display uses five white lights to signify progress toward your daily activity goal; users say this helps motivate them to get up and move. With no screen, the Flex requires you "to sync up with your iOS or Android device to garner any real data," says Paul Sawers with tech site TheNextWeb.com. He appreciates that the Flex "can record your sleep in 'sensitive' mode for detailed sleep reporting or 'normal' mode for a more general gist of your sleeping patterns." The Flex includes a vibrating alarm.
Effortless connection to most platforms. In a comparison review, Clara Moskowitz of LiveScience.com says the Fitbit Flex is "among the most inspiring and enjoyable of the fitness devices we've reviewed, in part because the wirelessly connected app provides a lot of data to allow you to work against goals and monitor progress." Experts agree the fitness support -- both through Fitbit's web account and mobile app -- is some of the best available. The Flex includes a wireless dongle and Bluetooth connectivity, syncing the tracker with most iOS, Android, OS X and Windows platforms.
Slender, discreet bracelet. The Fitbit Flex is smaller, less expensive and lasts longer between charges in comparison to other, bulkier bands. "Having spent several days wearing a Flex and forgetting it was there within a few hours of first putting it on, I think they made the right choices," says Duffy of Fitbit's slim design. The tracker itself is removable from the band, so users can change the look of the Flex. "For fashionistas, wristbands ($15 each) come in a variety of colors, including Tangerine, and the tracker device pops in and out," explains Christina Tynan-Wood of Family Circle. Reviewers warn that changing tracking modes and learning the accompanying app can be a little cumbersome.
Jill Duffy compares the Flex to Fitbit's clip-on One in this review. The Flex receives a rating of Excellent for its comfortable band, superb fitness app and easy data uploading; though Duffy prefers the One, she recommends the Flex for users wanting a bracelet-style tracker.
Review: Fitbit Flex, Jill Duffy, May 6, 2013
Editors at ConsumerReports.org test a handful of activity trackers, including the Fitbit Flex. Accuracy is tested using activity on a treadmill, elliptical machine and stairs and picking toys up off the floor. Testers also rate how well the device estimates calories burned, how easy it is to use and overall features.
Review: Activity Trackers, Editors of ConsumerReports.org, Not Dated
The Fitbit Flex earns a 3.5-star score and rating of Very Good from editors at CNET. Editors report the Flex offers simple tracking and syncing, but the real power lies in Fitbit's fitness platform.
Review: A Most Versatile, Feature-Packed Tracker, Editors of CNET, May 6, 2013
The Fitbit Flex is more accurate at measuring activity than the clip-on Fitbit One, says Danny Sullivan. He finds this especially important for non-step activities like paddle-boarding. Because of its comfortable design, helpful motivations and powerful fitness app, Sullivan prefers the Flex over the Jawbone UP and Nike+ FuelBand.
Review: My Life with the Fitbit Flex Activity Tracker, Danny Sullivan, May 12, 2013
Ben Taylor includes the Fitbit Flex in his "serious tracker" category: very good devices that are missing a key ingredient to become excellent. The Flex ranks higher than the Jawbone UP and Lark Life, but is a step behind its successor, the Fitbit Force. The Force has since been recalled.
Review: 26 Fitness Trackers Ranked from Worst to First, Ben Taylor, Jan. 9, 2014
Lee Crane gives the Fitbit Flex a score of 3 out of 5 stars. Its appearance is sleek and the automatic data syncing is much appreciated, but because of its difficulty in tracking non-step activities and some cumbersome procedures, the Flex isn't well suited for serious athletes.
Review: Fitbit Flex Review, Lee Crane, June 15, 2013
The Fitbit Flex ties for third place with the Withings Pulse in this comparison. Clara Moskowitz appreciates how comfortable the design is and how easy it is to sync data wirelessly. The LED lights motivated her to move more, but using the mobile app was cumbersome for some features.
Review: Fitbit Flex: Fitness Tracker Review, Clara Moskowitz, Oct. 2, 2013
In this comparison alongside the Nike+ FuelBand, the Jawbone UP and the Misfit Shine, tester Andrea Smith names the Fitbit Flex as the best activity tracker. She finds it has the best design and a long-lasting battery, is easy to sync and integrates with other fitness apps.
Review: The Best Activity Tracker: Fitbit Flex, Andrea Smith, Oct. 14, 2013
Paul Sawers combines the Fitbit Flex and Fitbit Force in his review of the best activity trackers, offering a snapshot comparison of the two devices. The Flex falls short of the Force with only a basic LED-dot display, but still collects a respectable amount of biometric data. The Fitbit Force has since been recalled.
Review: Know Your Fitbit from Your Fitbug: A Guide to the Best Activity-Trackers on the Market, Paul Sawers, Nov. 11, 2013
10. Family Circle
Christina Tynan-Wood tests numerous fitness trackers and provides a short write-up on each, but doesn't name a top choice or include a rating scale. Advantages of the Fitbit Flex include its changeable band and easy data syncing, she notes.
Review: Fitbit Flex Wireless Activity & Sleep Wristband, Christina Tynan-Wood, Not Dated
The Fitbit Flex is the number-one best-selling fitness tracker at Amazon.com, with well over 3,000 customer reviews, yet it earns an average rating of only 3.7 stars out of 5. In addition to complaints about durability, some say the wrist strap unclips too easily, resulting in lost trackers. Many love it, however, saying it motivates them to move more.
Review: Fitbit Flex Wireless Activity + Sleep Wristband, Contributors to Amazon.com, As of February 2014
After more than 1,800 customer reviews, the Fitbit Flex earns an average rating of 4.2 stars out of 5. About 90 percent say they would recommend the Flex to a friend. The fitness tracker gets plenty of praise for being easy to use, attractive, comfortable and useful.
Review: Fitbit-Flex Wireless Activity and Sleep Tracker Wristband - Black, Contributors to BestBuy.com, As of February 2014