Three weeks with a Fitbit Sense

So, I’ve had a Fitbit for nearly two years now. Specifically a first-gen Versa. (I used a Pebble and a Pebble Time previously.) I’ve enjoyed it, and when they announced the Sense, I pre-ordered it. I used it for about three weeks before deciding to return it. Here I will try to document my experience in case it’s valuable for others. I’ll try not to over-cover things I’ve seen in other reviews.

Mobile Pay

One of the things I was most excited about with the Sense is the mobile pay. After I bought my Versa in 2018, I realized for ~$30 more I could have had the mobile pay built in but didn’t want to deal with the return process. Unfortunately, the Sense has been a let-down. More than half the time I tried to use mobile pay, it didn’t work, just made me look awkward at the store. 100% of the time it didn’t work, Android Pay with my phone worked easily. Paying with my watch isn’t that much more convenient, if it doesn’t work 100% of the time then I’m just going to use my phone. On top of this, I usually had to put in the security code, which was additional friction.

The Button

The next thing I noticed is the solid-state button. It seems neat, but compared to my Versa it’s quite a pain. I found it difficult to push initially, though after a week or so I was ok at it. Sometimes it gets pushed by accident when I bend my wrist up, another issue that doesn’t exist with my Versa. I also found that once I felt like I was using it correctly, I would often get haptic feedback confirming I’d pushed it, but the watch wouldn’t do anything else (sometimes the screen stayed off, sometimes I just stayed on a non-home screen). I wish they’d used the same button as the Versa.

O2 Measurements

Another thing I was excited about is the O2 measurement overnight. It did work sometimes, but like the mobile pay feature, it failed to work >50% of the time. My interest in this was for an early warning of otherwise-asymptomatic COVID, so not working for 3+ days in a row is a deal-breaker for how much it costs and my relative certainly that it would actually be useful.

EDA Sensor

The thing I was most excited about was the EDA sensor. I have IBS, and log all my BMs, and I was excited to correlate this data with EDA results and see if I could come up with any interesting insights that ideally would lead to behavioral changes. Honestly this was the biggest selling point of the watch for me. My experience with the actual sensor was mostly positive, although there were times it didn’t work because the HR monitoring had stopped working, and the EDA “app” crashes if the HR sensor is having issues. All in all I was happy with it though, and the next thing I wanted to do was download the data…

Getting your data

In my mind, if a device is collecting biometric data on me, I expect to be able to get access to that data. Easily. On day one. Without having to ask for it. That wasn’t the case here, and I feel unwise for having assumed that I could have access to my own data. So, I contacted support and basically said I wanted to return the watch because this is essential to me. Support basically said to check back in 2 weeks. I did, excited because I hate returning things, but what they ended up delivering was not a new API where I could download my data at-will, but instead they added it to their bulk-download feature. Ok…

Bulk data download

So, I went to download my data. It took about a day to generate, which is a problem because I wanted to write software for nearly real-time (~5 minutes) processing. Then I found out that you have to wait 7 days to create a new full-download, which means worst-case 8 days of latency from when the measurement is taken. That’s a no-go.

So, I looked at the data anyway, because why not? For context, the data you get on the watchface is the number of EDA events in groups of 30 seconds over two minutes. It’s pretty useful – I often saw that I had more events in the first quarter, meaning I was calming down while taking the measurement, but sometimes it went up because I was ruminating. The data you download actually has raw measurements, nothing like what you see on the watch, and the measurements are taken every 5 milliseconds. That’s kinda cool, I like having that granular data, but it’s pretty frustrating that they expect me to reinvent the wheel to gain even trivial insights from the data; they should provide different levels of abstraction, or simple instructions (ideally code) for how to do the transformation (after all, it’s nothing proprietary). I don’t feel like we’re working together to enrich my life, I feel like I’m pulling teeth here.

The ZIP file I downloaded also had some documentation, e.g. for a field called “activated” it had the helpful description “activated”. Now I know! My impression is that Fitbit just isn’t invested in this part of their platform, and from my browsing of their developer forums, that’s unlikely to change unless you mention spending a lot of money.

I would actually share here a bit more about the data, but I accidentally overwrote it, and when I generated a new export file it failed to download, I got an error. I may update this blog with those details if Fitbit fixes it, since I do want to download my data before I leave their platform, but I wanted to write this blog post to give them more details before I tell them I’ve sent the watch back.


I had some more minor issues. Many of the animations feel long (e.g. hitting your daily steps), and tapping the screen does not skip them (I believe they’re unskippable on the Versa as well, but the animations never bothered me). On my Versa I can easily look back at which prior hours in the day I had managed to get 250 steps, but never found that information on the Sense. Turning my wrist to turn on the screen seemed to work less reliably than my Versa. I never figured out how to check the Sense battery from the watch, another easy thing with my Versa. I had to reboot the watch once because the UI got so broken, and it rebooted itself a couple times (that I noticed!) for no apparent reason; I’m worried about data loss here, though I didn’t dig into it. To use the wallet requires the watch have a security code that has to be re-entered once per day or if you take the watch off; I found myself having to do it multiple times per day, which is better than it accidentally letting someone purchase something on my behalf, but again it’s something not working as advertised (and honestly I keep the watch on as long as I’m not in the shower, so security is not a huge concern for me). I also signed up for health notifications, but it was annoying when they tended to come doubled:

The Return

Finally, after all this, I disappointingly decided to return it – a big deal for me, I don’t return things often. I’ve worked in consumer electronics in the past, and liked Fitbit, so I decided to purchase from them directly rather than via Amazon when I bought it. What a mistake! Amazon returns are dead simple – you walk into a UPS, they scan a QR code on your phone, you give them the product, and you’re done. Not so easy with Fitbit. When I requested a return, they sent me three emails, two of them asking me to print something (I don’t have a printer), and both those printouts having conflicting information. One had the address I was supposed to ship to, and the other was a shipping label.

I was really confused by this. I asked my apartmentmate, who’s also an engineer so presumably is at least kinda smart, and he was confused too. So I replied to support, saying “So, I tried to return this and got confused because it looks like I had to print a shipping label, but send it to a different address?” Their reply was, “Please proceed with the shipping label provided, the address is intentional” which didn’t help me at all – why send the other address? I procrastinated sending it out for weeks. I eventually went to the USPS yesterday, and the person working there was also confused by Fitbit in the same way my apartmentmate and I were, so I used the shipping label instead of the address because it was free for me.

What’s Next?

Well, I don’t see myself ever getting a Fitbit again. I’ve also become disillusioned with Google, who will presumably purchase Fitbit, so I don’t think a rebranding is going to help. So, what to do instead? I did some digging, and it seems like other smartwatches tend to have the same issue with data not being downloadable. I was somewhat interested in Oura Ring, though I would prefer a smartwatch, but when I contacted support asking for the CSV headers for the downloadable data (which I feel strongly should be publicly available on their website anyway) they wouldn’t give them to me unless I asked for a specific one.

A coworker recommended Aidlab, which seems to be researcher-focused and they have a well-documented API, and which I’ve ordered but has not shipped yet. The biggest issue with this wearable is that it’s a chest strap, so won’t do sleep tracking. I’m using my Versa for that for now, since it’s better than nothing, but honestly wearing a device from a company that has caused me this much frustration is not something I want to do. I have an old Pebble Time that I might try to revive, but haven’t gone down the rabbit hole on that yet. Withings looked the most promising, having API documentation, but it doesn’t have sleep depth like Fitbit does, so the only value it would provide over my phone is the at-night HR tracking which doesn’t seem worth it.


Honestly, I might just give up on smartwatches. When I originally got a Pebble (used!) I only intended to wear it long enough to get an intuition for it before I started writing code for it. I did end up creating my own watchface, but after that I just liked having a smartwatch and kept wearing it. So it’s a pretty old habit at this point, but I was fine before and I’m sure I’ll be fine in the future.