Trying out Fitbit Flex and Zip Simultaneously

Hi - I’m new here. Anyway, I just received my Fitbit Flex in the mail and am going to wear it with my Fitbit Zip over the next several days to see how they compare. I have a Jawbone Up and tested it against a Fitbit One (the up consistently undercounted by roughly 20%, which doesn’t strike me as that surprising considering it’s wrist-based)

Anyone out there in a similar situation and want to track data together?
I haven’t decided yet if I’m going to wear the Up at the same time since one will go on a dominant hand and the other nondominant.

Nearing the end of the first full day of wearing both devices.
My flex says 16,807
My zip says 19,651

Hello Victor,

I have been using a Fitbit one and a Nike+Fuelband bracelet. Recently I experimented by comparing Fitbit One, the Nike+Fuelband and also the “Moves” application which I use in my iPhone. The results were similar to your experience comparing Fitbit One and Jawbone. You can check also my results in slideshare:


Thanks for sharing. I have a friend who has a Fuel Band and has talked about how that overcounts for him due to extra arm movements.

My numbers yesterday for the Flex and Zip were:
Flex: 6560 steps
Zip: 9159 steps

So 39.6% more steps counted on the Zip. I was doing some odd movements relative to the day before - such as helping teach my kid how to ride a bike and thus my arms were locked onto the handlebar while I ran alongside.

And one more:
Flex: 10,606
Zip: 12,363

16.6% more counted on the zip.

I would like to see more of this! Please keep up the analysis and let us know how it goes. If you write up a post somewhere that would be awesome to share.

Just some generic comments about the Flex to add to this thread

Comfort wise: very comfortable. I don’t notice that I am wearing it. Compared to the Jawbone Up, it is more pleasant because it doesn’t catch or bump anything.
Ease of wear: This is where I have been less enthusiastic. Two issues. One is that it has to be disassembled to charge the unit. I went ahead and did that overnight and forgot to reassemble it, so yesterday I actually wore an empty bracelet the entire day before I realized that I forgot to put the unit back in. The other is the clasp. While Fitbit makes a point to say that it is waterproof and can be worn in the shower or swimming pool, I’ve been taking it off so I can keep the zip and flex on fair footing (I don’t give the flex extra steps by wearing it longer). Getting it back on is pretty tricky as it involves squeezing two little prongs into small holes that look like they belong to a minimalist wristwatch. You have to line things up very neatly and use a pretty firm squeeze in a tight space. As I use it more, I feel like the holes have a little more give, but it is still a bit of work to put on.

Anyway, my failure to reassemble the Flex yesterday makes it impossible for me to give a head-to-head comparison. I did get 9,478 steps, so my guess is the Flex would have given about 8120 steps had I remembered to wear it - and considering I was doing ‘normal’ activities.


do you synchronize both trackers to the fitbit site?

How the steps are counted on the fitbit site?

I have a fitbit one and think about buying a flex. But the altimeter is important for me thats the reason why I don’t want to sell my one. But is it possible to use both?



I synch both to the site but I have to use two separate accounts. They make the assumption that one and only one device is paired to an account. (I guess it is sort of weird to wear multiple). There is no altimeter on the Flex, which I would like to have - but it makes sense. It’s pretty hard to read elevation changes from arm movements.

My research team developed a simple, quick and dirty PHP interface to extract data as .csv from the fitbit site, but it still works through the fitbit accounts and pairings that are already established there.

If I was forced to pick only one device, I’d probably go with the One. The flex has some convenience to it, but I prefer to have more (and more accurate) information. With that said, the Flex is certainly a fine product to have if someone goes that route.

I will also go with my one. I lost it two times and got it back using the sync and alarm function.

Do you have an ApplicationID for your php script, or does it work without an ID?

I’m interessted in reading the raw data from Fitbit. How detailed is the data you get?

hmm…wish I thought about the alarm function. Unfortunately, the battery is dead so I can’t do that trick - but I’ll keep that in mind.

The phpscript is being migrated to a new server. I’ll post a link as soon as it is relocated. The current estimate is by the end of this week. It’s something quick and dirty we use in house for our projects (I head up a research group where we use these data and bring them to kids to help them learn STEM content)

I’ll make some sort of blog post about the long term data that I’ve collected on this comparison project at some point. I plan to pit jawbone and fitbit against each other soon.

I do want to mention that my fitbit zip has sort of reset itself a few times unexpectedly - I’m not exactly sure what is going on, but the time gets confused and I lose a day of data until I sync and everything straightens itself out from that point forward.

just heads up for anyone considering the investment. I personally like the ultra best of the devices I’ve tried, although the ‘one’ seems to be the intended replacement.

For anyone who is interested in accuracy, the NYTimes had an article on accuracy testing done out of some exercise science labs. When I get all of my own data (sans oxygen monitor), I’ll probably try to compare my findings to theirs.

Thanks for adding this link Victor. They didn’t link to the main piece of research they discussed. I was able to sniff it out and if you’re interested you can access it here: Assessment of Light-Intensity Activities and Sedentary Behaviors using Multiple Measurement devices. It’s on page s262, abstract #1380.

I got an email saying that I have a new response here. I recently posted something new on my blog on old data related to this. For those interested, see here:

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This is an old post, but I figured, someone else might be landing here from search engine, so I will post this anyway.

The Fitbi zip is arguably on the very low end as far as accuracy is concerned when it comes to comparison of fitbit products. The only benefit I can attribute to the device is that, it’s kids friendly as compared to other products that requires setting up an online fitbit account. This might come handy for kids younger than 13 years, according to this article.

Good luck.