FitBit Flex Review

WP_20140710_002 Yesterday I wrote about whether or not wearing a FitBit Flex actually changed how much I moved around each day (short answer: yes, most days, but not when I was such a slug that my goal was out of reach). This post is more specific to the FitBit Flex and the website.

How I Chose The Flex

There were a lot of fitness trackers to choose from. I was looking for certain features, and the Flex was the only one that had all of the major features I was looking for:

  • Counts steps
  • Can be worn on my wrist
  • Is waterproof, or at least water-resistant
  • Can sync with a computer, not just an app
  • Doesn’t cost an arm and a leg

It’s worth noting that since I expect to upgrade to something else at some point, there were some features that I would love to have, but don’t need right now. Touch-screens and detailed displays, heart rate monitors, stairs/elevation, longer battery life, and good looks are some additional things that I’ll be looking for when I upgrade.

I rejected the Samsung Gear Fit right away because it needs to be used in conjunction with an Android device. Likewise the Misfit Shine (which is very pretty!) and the Jawbone UP 24 (also very good-looking), both of which work with iOS and Andoid. I’m strictly Windows.

I said no to the Basis Carbon Steel, mostly because of the cost. It was tempting – it has a lot of great features and I like how it looks – but I knew that my first device would likely be somewhat temporary, so I wanted to go cheaper.

The Nike FuelBand SE was a close second to the FitBit, but it was way more expensive than the Flex. For that kind of money I wanted something…less sporty.

I considered getting a FitBit Force on eBay. Even though they’ve been recalled (and technically can’t be sold anywhere, even on eBay), the recall was for a dumb reason. But the ones on eBay were selling for way more than the original price, and when the Force is re-released it’s going to have some upgrades, so I didn’t want to spend more for an inferior version.

That left me with the Flex, which sells for under $100 on Amazon.

Looks Matter

When you buy a FitBit Flex you can choose from a bunch of different-colored bands, but the actual tracking device is the same in all of them.

You can buy different bands and easily transfer the Flex, but I was disappointed that the only difference in the bands sold by FitBit was color. I would definitely pay more for a more stylish band, something that looks more like a bracelet. 80-90% of the time, the sporty look is fine, but one afternoon when I was a bit dressed up I hated having the Flex on my wrist.

I’ve since found some pretty options on Etsy, but I’m still surprised that FitBit hasn’t jumped on this, considering you’re supposed to wear the device all the time.

The Display

With the Flex you don’t get any kind of fancy readout or screen. You get five dots. Each of those dots represents 20% of your daily step goal. Tap on the Flex twice and the dots light up to show you your progress (sometimes it takes me a few tries). Other than that, you don’t get any progress feedback on the device itself.


Yup, it’s after 5pm and I’m still on my first dot. I’m screwed

If you pay attention, you’ll notice that the closer you are to the next dot lighting up, the faster the last dot blinks.

Charging/Battery Life

I would have been much happier if there was a micro-USB charging slot in the Flex, but there isn’t, and it only took me three weeks to lose the charger it came with. I’d been keeping the charger plugged into my laptop at all times, but then I went on a trip, and the charger went into a bag, and well, you know how that goes.

I’d set things up on the FitBit site to email me when my battery was running low, and that’s when I realized my charger was nowhere to be found. I was sure I’d find it before the charge ran out, but I didn’t. By the time a new one came from Amazon my Flex had been dead for almost three days (three VERY active days, I might add!).


Third-party replacement charger. Works fine for less than half the money

The battery seems to last for about five days before needing a charge. You can extend the battery life by not using the alarm feature, not checking your progress so much, and not syncing as often. But all I do is charge it for a couple of hours while I’m working at my computer and not walking anyway. It’s charging now as I type this.

Plugging the Flex into the charger tells you how much battery you have left – the more flashing dots, the more charge. I do wish there was a way to find this out on the Flex itself, while it’s on my wrist.

You can see your battery charge on the app and on the website.


I generally only sync my Flex to my laptop, although you can sync to both a computer and a mobile app. Syncing to a computer is made super easy with the dongle (I love that word) that plugs into a USB port in your computer (and is included with the Flex).

Any time your Flex is within range of the dongle (about 15 feet), the computer is on and active, and there is new data to report, the Flex will sync automatically (it waits twenty minutes between syncs, so that you don’t drain the battery while hanging out near your computer).

You can also force a sync any time you want. Just right-click on the FitBit icon in your system tray.


FitBit starts you out with a goal of 10,000 steps a day. After a month of wearing the Flex I was averaging about 9,500 steps a day (not counting the days my battery was out) without trying too hard, so yesterday I increased my goal to 12,000.


Game-changing goal change – we’ll see how I do!

When you reach your daily goal, the Flex vibrates and lights up. The website calls you a champ and gives you a smiley face. It all feels very good, I must say. I’m a sucker for praise from inanimate objects.


The ONLY day I’ve ever gotten all greens! CHAMP!

If you’re competitive, you can also see how you rank next to your FitBit-owing friends. The rankings are based on your last seven days of steps. Until my battery ran out I was at the top of my friends board. Watching my ranking slip from top to bottom over that three-day period was SO demoralizing!!! I’m clawing my way back up, though.

The website also shows you the distance you’ve traveled, calories you’ve burned, and how many “active minutes” you’ve had. Each of these also has a goal that you can change whenever you want.

Sleep Tracking

The Flex also tracks your sleep, but not automatically. You have to tap it a bunch of times to put it in “Sleep Mode.” In sleep mode you can’t check your progress.

You wake the Flex up by tapping it a bunch of times again. I’ve found this process to be rather annoying. There have been mornings when I’ve had to tap it dozens of times to get it to wake up.

The Flex tracks sleep quality based on how much you move at night, and I’ve found this to be surprisingly accurate. On nights when I’ve had trouble sleeping, that was definitely recorded. On nights when I slept straight through like a log, that was recorded too. I’m not sure what use this information is to me, but I have it.

What would be useful is if I could keep a record of my total sleep each day – naps included – but I’ve given up. For some reason, putting the Flex into sleep mode before I take a nap does next-to-nothing. It sometimes records that as an “activity,” and with a click I can turn that into a sleep record. But most of the time it doesn’t even do that.

I recorded naps manually for a while, but I’ve given up. So most days it looks like I only got six or so hours of sleep, when I also likely had a monster nap in the afternoon. Oh well.

I’ve also found that applauding can put the Flex into sleep mode. At a recent concert I put it into sleep mode three times. Conversely, the other morning when I tried to wake the Flex up I found that it was already awake. When I checked the website it said I’d been awake since 3am, when I had actually slept right through the night really well. Was I tapping in my sleep? I don’t know.

None of that is a huge deal, definitely not a reason not to buy a Flex. But if they’ve bothered to have a sleep mode, I would like it to work properly, and it simply doesn’t.


The vibrating alarm function works well, and is a handy way to wake myself up without waking my husband up (except for the time my wrist happened to be lying on his head when the alarm went off).

You can set the alarm to be recurring or one time only. Note that any change you make to the alarm won’t take effect until you sync your flex.

The only time I ran into trouble with this was when the kids had a weekday off in June. I realized as I was falling asleep that the alarm was going buzz at 6:15am unless I went downstairs, turned on my computer, turned off the alarm, and synced. That wasn’t going to happen, so instead I was woken up early for no good reason. But that was my fault, not the Flex’s.

The FitBit website’s dashboard is very, well, flexible. You can add and remove information tiles and move them around. You can click on them to get more detailed information. You can look at past days and get totals for different time periods.

One thing that I initially thought was very useful, though, turned out not to be. I loved being able to see at a glance on which days I met my goals. Now that I’ve changed my step goal, however, it has changed the goal for the entire step history, making it look like I’d only made a my goal a few times! Very annoying. Makes the at-a-glance feature fairly useless.


Thanks for moving the goal posts on me, FitBit! :-/

All-in-all, though, the site is simple and easy to use.


I tested out the accuracy of the step counter myself. I started out on a walk when I knew that I was exactly 2,000 steps from my daily goal. I counted my own steps, out loud, as I was walking. According to the Flex, I reached my goal with only a four-step difference from my own counting. That’s pretty darn close!

I have not tested out the distance tracking accuracy. It works by estimating your distance based on stride length and steps taken, and if you find it to be inaccurate you can change the stride length used. I’m not sure of the accuracy of the calorie tracker either.

The “active minutes” tracker definitely suffers from not having access to heart rate info. Yesterday I did interval training in the morning, and took a long walk in the evening, both of which registered in the “active minutes” section. But this morning I did almost half an hour of weight training and planks. I was sweaty, I was breathing heavy, and my heart was beating fast, but the Flex doesn’t know any of that – that half hour didn’t register as active at all.

Worth The Money?

The FitBit Flex was definitely worth the money, although I would have gladly paid more for a FitBit Force if they hadn’t recalled it. The Force has a display with numbers, and knowing exactly how many steps I’ve taken, instead of a general idea, would be a definite plus.

Still, though, the Flex absolutely has me paying more attention to how much I move around each day, and that’s the ultimate goal.

UPDATE: For those of you with Windows Phones, there is now a FitBit app!


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