Charge 3 is showing accurate GPS map, but inaccurate distance

[SunsetRunner]

I've been using my Charge 3 for about two months now and noticed that often when I run, the GPS map accurately reflects my route, but the distance is quite a bit off. I tested this a few times by running the perimeter of Mile Square Park, a park so named because it's a square approximately 1 mile on each side (4 miles total).

Here are the conflicting data points (links to screenshots):

1. 3.93 miles: the distance according to Map My Run.
2. 4.01 miles: the distance my Charge 3 calculated, presumably based on my steps and stride length, when I ran the perimeter without connected GPS.
3. 3.35 mi: the distance my Charge 3 calculated when I ran the perimeter with connected GPS last month
4. 3.23 mi: the distance my Charge 3 calculated when I ran the perimeter with connected GPS today

As you can see in #3 and #4, the route captured by my phone's GPS seems accurate; it goes around the perimeter of the park, with no gaps. But somehow the distance is approximately 0.6 to 0.7 miles less than what it should be, which suggests that Fitbit is interpreting the GPS data incorrectly. Any idea what's going on here?

Moderator edit: updated subject for clarity

[MarreFitbit]

Welcome on board @SunsetRunner! Thanks for taking the time to share your results when using GPS on Charge 3.

Fitbit devices calculate distance by multiplying your walking steps by your walking stride length and multiplying your running steps by your running stride length. We estimate your stride lengths using your height and sex. Track one or more runs using on-board or connected GPS, we evaluate that data to automatically update your running stride length. For best results, run at a comfortable pace for at least 10 minutes.

If you prefer to measure your walking and running stride lengths yourself and enter them manually, see How do I measure and adjust my stride length?

Note that when you're tracking an activity with GPS, Fitbit calculates your distance using GPS data rather than steps. If you begin moving before you get a GPS signal, the tracker will calculate distance using steps and stride length as described above until a GPS signal is found.

Note that your device uses your step count to calculate distance until it finds a GPS signal. In this scenario, your total distance calculated for the workout may be slightly less accurate than if GPS data were available for the entire duration. For more information, see How accurate is GPS?

After reviewing this factors, please go for another run and see if the distance improves. 

Keep me posted! 

[SunsetRunner]

Thanks for your response, @MarreFitbit. I am aware of and understand all of the information you posted. However, it does not answer my question.

As I described in my original post, my Charge 3's distance tracking seems reasonably accurate when I am NOT using GPS, i.e., when the device is calculating distance based solely on steps multiplied by stride length. I have been running with it for a couple months now and the device has in fact adjusted my running stride length from the original "average" estimate, so I'm quite certain that recalibrating that is not the issue.

The problem is that when I run WITH Connected GPS, my phone appears to correctly track my route (as indicated by the linked maps in my original post), but the Fitbit device and/or app interpret the GPS data inaccurately, chopping off approximately 20% of the distance I ran. What I don't understand is, if Fitbit has an accurate map of my run in its possession, how could it still get the distance wrong?

In summary: Because I know my stride length is accurate, and because I can see from the maps it's not a problem with GPS tracking, my conclusion is that it's something on the back end with the way Fitbit is processing the GPS data. Do you have any information about that? E.g., is it something being addressed with a firmware update in the near future?

Let me know if you need any clarification. Thanks!

[MarreFitbit]

Hi there @SunsetRunner! Thanks for getting back and for letting us know about this issue. We’re aware of it, but may not be able to provide a fix in the immediate future. We'll continue to monitor the situation, and keep our team informed of the impact to you and other customers. We understand that this isn't the resolution you're hoping for, but rest assured we're always working to improve our products.

We're sorry for any trouble. We appreciate your patience and look forward to getting you back on track.

Please let us know if you have any other questions.

[Darragh42]

I am having the exact same issue. Like @SunsetRunner, I get back a reasonably accurate distance without GPS (based on stride length), but when connected with GPS I get back a reading often up to about 3km less per 10km of running than is accurate. Obviously this is a very significant miscalculation. This is despite getting back a perfect map. I can compare this to Runkeeper, which gives an accurate distance reading, despite displaying the same map. 

Also, like @SunsetRunner I have been through the boards and have read and understand the information relating to how the charge 3 works with and without GPS, how it connects to my phone, etc etc. 

I have attached images from a run yesterday evening, with Runkeeper measuring the run at 11.22km (about accurate) and Fitbit coming back with 8.14km (far shorter than accurate), both with the same map displayed.

Could you please let me know how to address this?

[briansok]

Interesting (in a bad way) I am having the exact opposite result. My GPS map is totally wrong but my distance is fairly accurate. Also my Fitbit is constantly vibrating during my activity. I am walking in the same park I always walk in and never had this problem till recently.

[deanjk]

I am having the same issue.  I'm losing 25% of my distance when using my Charge 3.

[4thturn]

Same situation with my Charge 3, a 6 mile walk is being measured at 4.75 miles...20% error is not excusable.

[deanjk]

I was hoping that the firmware update would fix this issue, but it did not.

--
Joel

[Rene2018]

Same issue here. My charge 3 is connected to my Samsung S9+ with gps on.

All bike, walk and hike exercises report wrong distances.

For example, a route that is exaclty 10km is reported by fitbit as 6km. The route map is correct though.

Any updates on this problem?

[deanjk]

My issue was with steps and distance. I ended up "fixing" this by walking a known distance and dividing the number of steps by that number.  The stride length is not even close to my actual stride length, but the distance I walk is accurate now.

[RebaRose]

Has this issue been resolved yet? I started having this same issue with my Charge 2 about two weeks ago. The week before it was calculating correctly and then it said I ran a half mile shorter when I ran the exact same distance as the week before. So I thought it was my Charge 2 and bought the Charge 3 just to try it out for the first time and it's doing the exact same thing!! Which makes me think it has to do with the app and not the device. I have always been connected to the GPS.

This is very irritating. These devices aren't cheap and should be made to do what they are advertised to do.

[klm0968]

Like the other users in this thread, my Charge 2 works well when using stride length to calculate distance, but badly under-reports distance in GPS mode even when the map is drawn pretty well. This morning Fitbit reported 2.47 mi on a route I have repeatedly measured with a Garmin GPS unit as 3.248 mi. That's around 25% low, similar to other users. It is as if the software isn't correctly calculating distance from otherwise (fairly) accurate GPS data points. A software fix would be pretty straightforward, I would think. Please let us know this issue will be fixed soon.  

[RiseAndShine]

Replacing my original post with an update. Went for a run this morning and  - oh miracle! My C3 was actually showing expected pace and distance... for the first time since my last accurate GPS run on Sep 12th (has been using it almost for a year without much trouble till recent changes took place). Now I wonder if Fitbit made some "interpretation tweaking" on their part? Cause after endless playing with settings, restarting, resetting etc  I couldn't get anywhere, and all of the sudden it now works as before?

[OldBob3301]

I'm with all of the other users of this thread.  I'm about to give up on using a connected gps with the C3.  I can't imagine what the problem is with connected gps, although I have some suspicions.  I picked a point on my route and checked it with google ... as the crow flies, it is 1.3 miles from my house, but 1.5 miles as the walker walks.  So, perhaps the algorithm Fitbit is using needs work.  It's annoying because not only is the distance wrong, but other measurements derived from distance are also way off ... such as pace.  If I exercise with the gps ON my fitbit records my performance as about 20-30% slower than if I exercise by counting steps I'm miraculously faster.  

[atjain]

I am observing the same issue with my Charge 3. Its not getting the correct distance though the map is showing correctly. 

[ekivisik]

When can we expect this to be fixed? It was ok for a few months at first, and now in 2020 I have never gotten a reliable distance with Connected GPS. The gps map track is fine, but distance is way off. Endomondo shows same track but correct distance (using the gps on the same phone).

[FriedaGG]

Having the same issue with a Charge 3 using a Samsung Galaxy S9 to track GPS. Route is correctly tracked according to map and, but the Fitbit app reports the distance almost 1.5 mi too short on a 6 mile run. I have been using this device for almost a year now. Had the problem at least once before and it seemed to be resolved after a while, but now the problem reappeared in March 2020 and has persisted for several runs.

[Watched]

Since it's been over a year since your response, I'm wondering if a fix has been found. I am consistently seeing these miscalculations.

I understand that there are two mechanisms for the calculation: GPS and steps (where steps are used when GPS is missing). It would be great if you could disable the steps calculation and just interpolate distance from the reported GPS points. I can't imagine that would be a difficult patch...

[Jring000]

I have had the same issue. Went for a run a couple weeks ago and thought the distance was short based on the maps of the path. Today I ran the exact same path and the distance was even lower than the previous run. In both cases I was using the phone GPS and the map displayed the rout correctly. 

So I decided to test it and did a shorter run using my Fitbit Charge 3 connected to my phone GPS and my MayMyRun app connected to the same phone GPS. I started and stopped both at the same points.

When I looked at the results both apps mapped the rout just right BUT the MapMyRun app showed the distance as .73 miles and Fitbit showed .67. Over a longer run this would make for a big difference. I should note that according to the parks map the trail was .74 miles.

I do not understand why Fitbit cannot get this right. I use my pace frequently when running and it is totally messed up because of this. I've been trying to deal with it for over a year. Any help or explanation would be appreciated.