Product Review: Fitbit Ultra versus Flex

First, I’ll give you the punchline. I returned the Flex and went back to my Ultra.

Now, the story.

I got my Fitbit Ultra a bit over a year ago now. I love it. It has quite literally changed the way I live. I walk daily and I’m healthier and happier both physically and mentally. When I saw the wrist-worn version, Flex, I wanted it. Basically, I wanted it to count all the thousands of steps I’m sure I take in the shower, I guess…. that and the wrist bands had other colors, so I could change it up. When it came out, I ordered right away – and it was already on backorder along with the multi-pack of all the colors of wristbands available. So, I waited.

I was super excited when I got the email telling me my Flex was shipping (the wristbands were on a much longer backorder and I ended up never getting them, because as I mentioned – I returned the Flex).

I’m a scientist at heart and by training. There was no way I was going to skip the “do the experiment” phase, especially since a twitter friend, @clearwriter, had a Flex and had indicated she wasn’t as happy with it as she wished.

So I wore the Flex and the Ultra together. One on my wrist, one on my hip. I already knew the Ultra was amazing at getting the step count right. I could count off 100 steps while walking and it would show 100 steps logged. I trust it.

I was able to get a direct comparison because I signed up with the Flex as a new user with a different email account. I had the Flex open in one browser and the Ultra in another, so I could see both simultaneously.

The first day, the Flex and Ultra reported very similar counts, and I was pleased. It took some getting used to that the Flex doesn’t have a readout and only shows you progress towards goal, but once I understood the importance of the speed of the flashing dots as well as their final number, the math was reasonably easy.

Day two, the Flex appeared well behind the Ultra. So far behind I began to wonder if it had reset my step goal to match the previous day’s excessive steps. When it finally vibrated to celebrate reaching goal, I should have been close to 3k steps beyond my goal. But as it does not sync to my kind of phone, I had to wait to get home to see the actual number. It was not good, and I made a screenshot of it to share on twitter:

Fitbit Issues


I contacted Fitbit support online. I got a form email telling me that since it’s on my wrist it might overcount depending on the activity I do with my hands. I noted that overcounting was definitely NOT the problem. I did try switching to wearing it on my dominant wrist but not telling the device this and if I was doing something like gardening then I got the overcount – but if I had told it it was on my dominant wrist I don’t know what would have happened. Massive undercount I imagine.

One morning I took a brisk 6 mile walk at a 4mph pace. I carried nothing and kept my arms swinging by my side normally. I used a GPS tracker on my phone to be certain of the mileage. The Ultra tracked perfectly, the Flex was very far behind (see below for the immediate screen grab after I got home).

fitbit issues part 2


I reported this to Fitbit support and was told I should update the firmware – they even told me what firmware version was on my device and the firmware version I should see after the update. Unfortunately, even after trying this several times (after I returned from an out-of-town business trip and could access my computer again) all I ever got was this:

fitbit issues part 3




I gave up. I asked to return it and only because I had ordered direct from Fitbit was I able to do so. That went smoothly, at least.

I did go and look at the nearly two weeks I wore both and tabulated the data:

Fitbit summary

If Flex had been within a few percent even of the Ultra, I’d’ve probably kept it. But this sort of undercounting (and overcounting would be just as bad, maybe worse) is simply unacceptable.

My Ultra is going to crack in two at some point – but then I will get a One instead. I have a friend who has a broken-in-two-but-still-functional-Ultra and a One and she is now wearing both to confirm for me that the One is as reliable as the Ultra. So far, so good.

Bottom line: I love Fitbit and the community support and I am thrilled I have mine. But I was terribly disappointed in how inaccurate the Flex was, and how unable the Fitbit team was to understand why or fix it.

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