Is there a way to improve Sense GPS accuracy?

[mmalach]

I'm unfortunately finding the Fitbit Sense GPS to be very inaccurate.  I've accurately measured a couple of my running routes using a couple of different mechanisms (and they are all in agreement).  The Fitbit Sense is consistently measuring my routes as short by approximately .1 miles per mile (i.e., my 4 mile route is being measured as 3.6 miles).

Is GPS accuracy dependent on where you live?  Is there a way to improve GPS accuracy?

Moderator Edit: Clarified subject

[t.parker]

The problem isn't in the GPS. In my tests, I find it quite accurate. The problem is that GPS doesn't contribute when it comes to distance computation. Changes in stride length (caused by changing cadence or running uphill/downhill) will affect the total distance on the same route. There is no way to correct it. It's been working this way since..well..ever and Fitbit doesn't consider this issue to be a bug.

Here's the test I've done:

https://community.fitbit.com/t5/Sense/Is-Fitbit-Sense-for-runners-test-of-GPS/m-p/4665596

As you can see, GPS data is actually quite correct, yet the distance wrong.

[Rich_Laue]

With a run gps and stride are suppose to be taken into consideration. The more a curate the stride setting, the more accurate the distance. Now Fitbit says that the run stride has the ability to self adjust but it takes several runs. How many are several? 

On a walk, we haven't had any confirmation how it works, however many people, including me, doing their own tests seem to agree with @t.parker.  

[natefrog255]

I agree with t.parker.  When I check the GPS after my run, its generally pretty accurate.  My issue is the distance is always short which kills my minute per mile calculation.  I've been hopeful that the more runs I did that it would maybe adjust to my stride over time, but the distance is still coming up short.  I've started using Strava again on runs which I feel is generally pretty accurate all around.  The other odd thing is FitBit will auto detect my run (without GPS) and the distance/minute per mile always ends up being really close to Strava and more accurate.  Definitely a little disappointing though that the GPS feature has been lackluster as that was a feature I was looking forward to, even though I still have to take my phone with for music since the Sense doesn't have SiriusXM or Amazon Music which is what I use.

[GaryP22]

I have the same issue.

As Stand up Paddle boarding or kayaking is not an activity I have tried logging it as swim and a walk and others. They all track the map perfectly, yet 5miles = 1.4 miles in all cases.

Then today on a bike ride my with my wife, her fitbit Versa logged 4.2 miles yet my sense logged 2.9.

Thefore the stride length calculation is utter nonsense.

Any other bright ideas please.

Or its going back.

[Rich_Laue]

@GaryP22 have you tried Outdoor Workout? 

Sundae Swim doesn't have the option to enable GPS, you sgoukdfnit have any distance recorded. Unless your paddling records laps, and in this case, the distance can never be accurate. 

[GAIslandGirl]

The mileage on my Sense watch and my Fitbit App when I walk is very different. Before my walk, I'm depressing the Exercise, then Walk feature on my Sense watch, as well as the Exercise GPS tracking feature on the Fitbit App on my phone. The Fitbit App is showing I'm walking 4.06 miles, while my Sense watch is showing I've walked 4.98 miles. Both of the walking routes appear on my Fitbit App, showing the different mileage, but the same route. The "time" for the walk is the same on both. Since both indicate they are using GPS, I'm very confused. Any thoughts and/or suggestions? Thank you.

[natefrog255]

Since my comment in July I had to buy a new FitBit and went with the Versa 3.  I still have issues with the GPS short changing the distance I ran.  For example on 10/10 it both auto detected a run and used the GPS.  The GPS came up with 2.89 miles and the auto detect at 3 miles.  Strava was around 3 miles, which was accurate per my pre-run distance calculator.  But that .11 mile difference makes a huge difference on Minutes per Mile.  I have no idea why the FitBit Sense and Versa 3 struggle with the distance so much.  I had much better luck with my Versa 2 which I could rely on as being accurate.  It has to be the internal GPS is not as good as being able to connect to my phone GPS b/c that is the only difference between the Versa 2 and my new watches.   It is kind of annoying though that I have to run the Strava app vs just being able to start/stop with my wrist.  

[Rich_Laue]

@GAIslandGirl or you saying that you use both the fitbit app, and the watch, to record your walks? 

Make sure both have acquired a GPS lock before you start walking. 

The fitbit app strickley uses GPS while the watch uses both steps and GPS. Make sure that your stride leangth is correct. 

[GAIslandGirl]

Thank you for the quick replay. 

Doesn't the Fitbit Sense determine the stride length automatically?

I don't understand what you mean by GPS lock. On the Fitbit App, on Days of Exercise this week, I press the plus (+) sign. This takes me to a map of my present location before I begin my walk, which appears to be the GPS signal is working. On my Sense, I press Exercise, then Walk, and it shows the GPS connecting, so I believe that is working as well. 

Regarding the stride length, I don't see any feature to add this to the Sense. And again, I thought it was automatic, as well as understanding that my stride length varies throughout my walk.

[GAIslandGirl]

Also, I'm a Walker, not a Recovery Runner, so I'd appreciate help on how to correct that on this forum. Thank you.

[t.parker]

@GAIslandGirl Recovery Runner is your current "level" as a forum member. It just depends on your posting etc. It means nothing.

[GAIslandGirl]

Oops! Apparently the title Recovery Runner pertains to my input into the forum, not what I do when exercising. Sorry!

[GAIslandGirl]

Thank you! I figured this out after receiving an email regarding the change
to my status. But Thank You for the information!

[natefrog255]

If you go into the app and click into Your Account, Activity and Wellness, Exercise, and scroll down to Stride Length; you'll have the option to automatically calculate or manually enter numbers for walking and/or running stride.  I have generally left mine as automatic and it hasn't been working for me.

I also don't get if I get a GPS signal on my wrist when I start my run via the Exercise option, why my stride length comes into play UNLESS my GPS signal drops enough to where the inaccurate stride is causing the problem.  But its back to a FitBit issue b/c why would Strava app on phone calculate it right via GPS but not my FitBit watch.

[t.parker]

@natefrog255 stride length shouldn't be used as an input data but who knows what Fitbit does. For walking and running using GPS alone wouldn't be effective (GPS isn't accurate enough for slow moving objects). Usually, all the sensors participate and that includes GPS. Many data streams make it easier to find errors (like issue with accelerometer drift) and correct each other. The stride length in all cases I know is the output, however, if computed as an average for run/walk using GPS it may serve as data correction for non-GPS walks/runs. Basically, using stride as input for calculating distance is wrong. Stride is very variable. Yet, using GPS only won't work either. It may not be that visible as GPS errors would get smoothen but the live metrics would become mess.

[Rich_Laue]

Yes stride leangth should not be used, unless the watch loses a gps connection. Then it is helpful to have a correct stride. 

In the past fitbit did use both gps and stride. 

[GAIslandGirl]

Thank you. But again, I don't understand why both GPS mileage results are different when both my Fitbit Sense and Fitbit App are started together before the beginning of my walk. 

Which one is accurate - and why aren't they synced?

[t.parker]

@Rich_Laue how do you know what stride is "correct"?

@GAIslandGirl app uses different method of measuring distance and watch uses different.

[Rich_Laue]

@t.parker there are several ways you can find with Google. 

How do I do it. I use Google pedometer to mark off a mile. 

Then use the manual start of the walk function. Or count every left step and multiply by 2. Then walk this mile. 

A mile is 63,360 inches. Your stride is 63360/ steps