Versa 4 won't track my distance accurately

[cantfineanswer]

My versa showed 2.33 miles and my samsung galaxy watch showed 3.0 miles and my charge 5 walking the SAME DISTANCE also said 3.0 miles. What is going on. As a tracker its not tracking correctly. 

Moderator Edit: Clarified subject

[MarreFitbit · Accepted solution]

Hi there, @cantfineanswer. Thanks for stopping by in the forums and sharing the details about the issue with your Versa 4. 

Fitbit devices use the formula below to calculate distance. Your stride length is determined by your height and sex. Steps x Stride Length = Distance Traveled

Please note when you track an activity with GPS, your device calculates your distance using GPS data rather than steps. If you begin moving before you get a GPS signal, your device calculates distance using your steps until GPS connects.

To update your stride length, track a run with GPS or measure your stride length manually. For more information, see Can I change my stride length in my Fitbit account?

For more information about GPS, see How do I use GPS on my Fitbit device?

[cantfineanswer]

thank you for responding. I have a charge 4 and samsung watch 4. Both are in sync and reflect the same distance have tested multiple times. Yesterday i wore the samsung and the versa . Samsung reflected correct mileage 3.0 and Versa showed 2.33. Did this same exercise wearing samsung and fitbit charge and both reflected 3.0 miles and were in sync along the way when I checked. I walk the same path daily and both of these devices reflected the same accurate distance. Not sure why versa 4 is so off. 

[cantfineanswer]

Today I walked a mile (1760 yards)  according to previous measurements and tracking. My steps were 1916 according to versa. I started at 7925 and at the mile was at 7925. My stride is showing 24.7 but when I do the math that is not correct. Can you explain and help me? If I am going to bother tracking then I want it to be more accurate. Thank you

[SunsetRunner]

This has happened before to multiple people and it is very common because the Versa 4 isn't accurate with distance and GPS.

[cantfineanswer]

So what's the point if having a fitbit versa tracker

[Ciderfit]

It's an expensive gimmick - came free with my phone as I'd never buy one 

[cantfineanswer]

Issue continues. 1.5 mile discrepancy. Answering calls doesn't work either . Will never buy another fitbit. 

[t.parker]

@cantfineanswer is the route hilly? The hilly (and steeper) the worse the distance measuring accuracy. There's not really much you can do about inaccuracy. You may try to change your stride length but (speaking from my experience) I don't recommend doing it unless you really know that length. What @MarreFitbit said, is that Fitbit calculates distance as Stride x Steps is either far from the truth or the algorithm has been developed by a first grader. The stride length is never constant, it fluctuates a lot and it is really tricky to compute distance just based on that. Usually, it must include some intensity factor (for example, the more you wave your arms the faster you walk/run, not always true but may be used as one of assumptions). The simplest way of computing the distance can be expressed with an equation:

Σ(IF*stride_length*dSteps)

The problem here is that if IF (Intensity Factor) is off or stride_length then the distance will be off, too. The distance can be computed only as a sum of short segments because using an accelerometer causes very quickly a drift (so distance increases exponentially). Fitbit has two stride lengths, one for walking and one for running. Now, I've been trying to figure out how it may be involved and I believe the walking stride is the lowest stride while the running stride is considered the highest. Using an IF watch will try to find out what stride the user may be walking/running with at the current time and multiply by the number of detected steps. The shorter the time period, the more accurate (until a certain degree) the distance would get. Steps can be detected from vertical motion (bouncing while walking/running or speaking more scientifically, from VO - Vertical Oscillation). The intensity would involve horizontal motion and that will be mostly the motion of the arm (yet it may involve VO + horizontal motion). And this is a very simple distance computation designed not by a first grader (yet still very primitive). The more sensors watch has on-board, the more complex it may become (and in reality, it is a lot more complex than stride x steps).

If you look at the data from foot pods (sensors you put on your shoe which can estimate distance) you'll find that average stride length is always different. In other words, entering it manually makes very little sense.

Below example. Same route (5K Parkrun race), with different intensities. Top: high and almost fixed cadence, racing pace, Bottom: variable and low cadence (ran it with my wife), jog/run (not a walk, though).

The white line represents stride length changing over time. It's not only that it's not constant but it's very different for both runs (1.29m and 0.84m). If you look at the elevation (the course is slightly hilly) you'll see stride length decreasing on inclines and increasing on declines. The pink line is cadence (steps per minute). Most amateur walkers/runners have an unsteady cadence (bottom chart), while trained runners have it almost constant regardless of elevation (top chart). Fitbit deals better with the first case so for me (I normally run like in the top chart) the distance is usually computed with a large error. A higher cadence isn't Fitbit's friend either. There is a larger error when I run 200spm (usual for trained runners) than 164spm (amateur runners).

This shows how many different factors the algorithm has to take into account in order to estimate distance closer to the real one. Saying Stride x Steps is just misleading because users try to calculate it by taking either walking or running stride and a number of steps and it never adds up.

We know very little about Fitbit's algorithm, however, there are a few things you could do to improve things (it may work or not):

- use automatic stride length
- use GPS (make sure it's connected) and let adjust the stride length using GPS
- do the above for Walk and Run (I don't know whether one or both stride lengths are updated so better to perform both activities)
- when you walk/run try to wave your hands naturally (feel the momentum).
- don't overstride or understride (ie. walking in place).

This may help as it adds easily recognizable patterns to the motion. My assumptions come from experience with other watches and working on similar algorithms. I am not sure whether Fitbit does it the same or similar way but there is a chance that the code is not written by monkeys. Give it a go. If it doesn't work for you, Fitbit isn't the only brand in the market.

[cantfineanswer]

appreciate the detailed information. I am not a marathoner. I simply want a device that correctly tracks my miles when I walk. My samsung watch does this. Had hoped the fitbit versa 4 would as well. The charge 5 was alot more accurate