Mygpsfiles

[James Talbot]

Was doing cross country skiing, and set activity to "run" (as there is very limited activity list). Had phone connected, and got perfect GPS route on Fitbit activity. However, all the splits are way off. Total distance in Fitbit shows 4.8km while real distance was 7.5 km (I know the route, and even double checked via ontegomap.com).

How can Fitbit calculate distance so wrongly even though the GPS route is perfect on the activity? I repeat, the tracked route is 100% correct on the Fitbit activity in question, so there is no disconnections, or trees, or anything between the phone and GPS satellite, nor between phone and Charge 3.

OK, just did a quick check by walking 1.82 km measured using onthegomap.com, tracked with Runkeeper, the Fitbit app and my Charge 3. Runkeeper was correct at 1.82 km, the Fitbit app was 1.83 and the Charge 3 at 1.79 set on automatic stride length. Pretty close, but I really don't understand how the Fitbit app gives a different, albeit slight, different distance. After all, both apps were on the same phone, using the same GPS, I would have thought the distances would have been equal.

I have found the same inaccuracy. I have been using a cheap throwaway fitness tracker for a while and decided to get a Fitbit. My usual walks are around 5 km, but the Fitbit shows much less. I decided to wear one on each wrist to compare. The cheapie showed 9536 steps for 6.56 km. The Fitbit recorded 7337 steps for 5.11 km. So the steps per km for both are the same. To find out which of the two was more accurate, I walked 300 steps counting them as I went. The cheap fitness tracker recorded exactly a additional 300 steps, but the Fitbit was 16 steps short. I think that the further I walk, the more inaccurate it becomes. This morning my walk would have been about 5.5 km, bit Fitbit said it was 4.03 km.

Yeah, wish I'd looked at these posts before I bought my Charge 3. But instead I looked at all the reviews of Fitbit gear online, more fool me, I suppose. The inaccuracy doesn't seem to be too bad on mine, but I'd much prefer it to be more accurate. I'll keep going with it and see if the inaccuracy is consistent. At leas then, I'll be able to make the necessary adjustments.

TL;DR: Fitbit support today confirmed that there is a known issue with underreporting distances and they are working to identify a resolution

Update - I called Fitbit Support yesterday about the issue, because I have continued to see the same problem (although now it is averaging about 15% underreporting error)

Yesterday, they had me reset and reset the Charge 3 while I was on the call (I don't know if they did anything on the back end) and I had also uninstalled the app (including clearing the cache and local storage).

Since then I did a walk yesterday evening and a run this morning and still had the same under-reporting problem so I called back with the same case number

The Fitbit support looked into it and came back with confirmation that there is a known issue with some user databases under-reporting distances at the moment, which was confirmed a problem in their system on May 1st. It is impacting users worldwide but not all.

They are "working to identify a resolution as quickly as possible". So, good news in that there is now acknowledgement of the problem and they are working to fix.

@SgtPepper great to hear FitBit is acknowledging this as an issue, hopefully it can be investigated and resolved quickly.. Did you get any internal reference, so we can advise support of related issues?

I'm intrigued that it isn't a problem with all users. You'd think that if it was a problem with the software, then it would be the same for everyone. That is, of course, provided that everyone gets the same updates at the same times, I suppose.

Looking at the distances of my past runs on exact same route, there is perfect GPS route drawn on the exercise map on each of them, yet the measured distances vary like 30%. Support has been unable to answer how Fitbit can draw exact route YET measure the distance differently each time.

I keep checking everyday for an update that will fix these problems, but so far no joy. I'm going back to using Runkeeper to track my walks and runs. At least that way I get reasonable accuracy and usable voice prompts. When my Charge 3 dies, I'll be buying a pedometer and heart rate monitor, I'm not game enough to even consider getting another so-called fitness tracker.

@BertilDator I'm seeing the same discrepancy between the distance FitBit calculates and the GPS route, therefore it seems the distance calculation does *not* use the GPS data, otherwise the results would be more accurate..

Despite mainly relying on a Polar Ignite watch, I am still curious about this deficiency in Fitbit devices so I often take my Versa 2 watch along for comparison. In addition, I often run the MyTrack app on my phone as this uses the same GPS source as the Versa 2.

- The distance recorded by MyGPSFiles is always higher than that given by any of the 3 apps by as much as 5-10%. I presume that this is because MyGPSFiles is simply adding up the distance between the points in the tcx file whereas the apps are using some sort of smoothing.

- So the egregious errors shown by Fitbit must lie in this smoothing process. On a walk that I clicked out on Google maps to be 1.83 km, MyTrack fairly consistently returned 1.8-1.83. Versa 2 went down to 1.4 km though it did sometimes return 1.8. The Ignite watch, with its own GPS source, returned 1.75 - 1.8.

- As to why it is so inconsistent, I can only assume that the processing by Fitbit is inordinately sensitive to variations in the GPS track which will occur because of variations in satellite postions and changing tree cover. Some people have suggested that Fitbit is using stepcount and stride length and ignoring the GPS data. I can't really believe this but it could be easily checked by fixing the stride length manually in the app and recording the stepcount before and after.

@mfergo I haven't been using any Fitbit device for a very long time but I revived my wife's Charge 2 yesterday (surprisingly worked!) as my one didn't turn on. I wanted to test something different but today I took it with me for a bike ride. Same as Charge 3, Charge 2 relies on the connected GPS. My findings are similar to yours. I compared the data with another GPS watch. On 24km (23.9km) Fitbit chopped off over 1km. However, after uploading the TCX to mygpsfiles the track perfectly overlaps with the one I captured with sports watch. The distance computed by mygpsfiles is also very close. Not a surprise, as I have seen this years ago. I just hoped it might have been finally fixed. Good old Fitbit, never changes anything for better

About walking/running do a simple test. After connected GPS is enabled, try to walk in the spot and see the distance. On Charge 2, the distance is going up because for those activities watch uses steps and stride rather than GPS data. I see no reason why it would be any different for Charge 3. I think I have to retire this device for good

@SgtPepper, you know what, 1st May fits with my issue very closely indeed. Until quite recently my Charge 3 connected to my OnePlus 5T for a 3.25 mile walk was tracking very closely. The margin of error was only about 0.1 miles, quite acceptable.

A error margin of 16.6%, or a sixth, is very bad. As with everyone else here I know the perfect distance of my (same daily) route, and have measured it with Google Earth's path plotting tool for reassurance. The step count is also very close each day. -- Just not the distance. Unfortunately this also seems to impact the pace figure because the Fitbit doesn't think I'm travelling as far as I am, which no doubt also impacts the energy it thinks we've burnt.

Same is happening to me. I track my run from my Fitbit, through the exercise shortcut, and wait for it to advise that GPS is detected (I also take my phone with me on my run). However it will only say that I have run 3.5km when in fact I have done a 5km circuit.

This has been a problem on multiple forums and there doesn't seem to be an answer? I have now been using the strava app to track my running distance which is the whole reason I bought the fitbit in the first place!

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