inconsistencies in measuring distance

[heeemz]

Off late, I see my IONIC is way too erratic in measuring distance during walk, run, cycling etc... 

Walk - Walking track is measured, each circle is exactly 500 meters, but IONIC measurements tend to go off by 50 to 100 meters, sometime shorter or sometime higher... Is that an issue with calibration? But how to calibrate or re calibrate? 

Run - During recent event I participated of 8 Kms, my IONIC calculated as 7.55 Kms, I checked with few others having smart watch, it calculated nearly accurate. 

[SilviaFitbit]

@heeemz Welcome to the Community. Thanks for the details mentioned. 

If you feel that your step count and distance are inaccurate, confirm the following are correct in the Fitbit app:

• Your wrist settings (For more information, see Does the wrist I wear my device on affect accuracy?)
• Your height (For more information, see How do I manage my Fitbit profile?)

Since we use height to estimate your walking and running stride lengths, you may want to measure and manually adjust these values if your legs are longer or shorter than average. For more information, see How do I measure and adjust stride length for my Fitbit device?

If you're tracking your exercise using GPS, all devices with GPS sensors require a direct path to GPS satellites to calculate location. A weak GPS signal might affect the accuracy of your route and other activity data. Your device uses your step count to calculate distance until it finds a signal, so the total distance calculated for a workout may be slightly less accurate when GPS isn't available for the entire time. 
Sometimes, when you start walking, your steps may not update on your device right away. After about 10-15 continuous steps, you'll notice the steps catch up and start updating in real time with each step you take. Could you let me know if your Ionic is loosing GPS? 

Keep me posted. 

[heeemz]

1 - if the settings you have mentioned were incorrect, why did it work OK so far?

2 - Height and Wrist settings are accurate, assuming if they were off (just in case), the distance measurement should follow pattern, isn't it? but that isn't the case as well. As indicated, the measurements are off, sometime less than actual or sometime more than actual

3 - Yes, this watch does have GPS issue, and I have another thread opened for same, BTW - distance measurement goes off on treadmill as well. That's ridicules.

[t.parker]

Nobody really knows how the device computes distance, not even Fitbit employees considering replies which are either irrelevant or contradicting to each other.

One theory says that even if you use GPS the watch still uses steps and stride to compute the distance (I believe only in case of walking and running, not cycling). Then such mismatch between real and calculated distances is in fact unavoidable. There is no chance you're going to walk or run with fixed stride and every step is going to be a real one (watch doesn't count steps but arm swings). The same theory says the GPS is used only to adjust your stride length. It may be truth considering that in most of cases if you download the TCX file containing captured GPS data and run it through any mapping software you'll find out the distance of the GPS route is correct and only Fitbit shows wrong numbers. This disprepancy was always there and I just stopped using Ionic for running. There was no other solution (and I see there is no one till now). It isn't runners watch. It isn't sports watch.

Treadmill is an entirely different story and the distance cannot be easily computed without additional hardware (like foot sensor, for example, Stryd). No wrist-based device will be able to compute distance on the gym machines unless they can connect to the foot sensor (watches from Garmin, Polar or Suunto can). With Fitbit all you can do, if possible, is to edit final details to match what the threadmill shows you.

[heeemz]

I agree, at the end of the day we are looking for consistency from FITBIT. Minor deviation is OK... but consistently inconsistent with varied gaps is bad...

[Rich_Laue]

@heeemz while on a treadmill Fitbit can only use steps and stride to take a guess at the virtual distance traveled. Unfortunately stride will change as the speed changes. 

When it comes to outside, several users have tested this and found that while walking, the gps is not used to measure distance. 

Another point is that people generally have a slightly different stride from day to day. 

[heeemz]

@Rich_Laue  Thanks, I agree and completely understand.

I added details around outside and treadmill to provide broad overview of distance measurement go off irrespective.

As an example -

1 - 8Kms run calculated by IONIC as 7.55. This was an outside event, not treadmill. Couple of my friends accompanying me for this run, had their watch (one had FITBIT and other had iWatch) doing correct reporting. Which is why I asked - does my watch need calibration? and if yes - how do I go about it?

2 - The walking track I use on a regular basis is accurately measured, each circle is exactly 500 meters, but IONIC measurements tend to go off by 50 to 100 meters for each round of circle, sometime shorter or sometime higher

[t.parker]

@heeemz this is because any watch with GPS will use GPS to measure the distance. For some reason, Fitbit doesn't seem to be doing it. My guess is it's because of legacy reasons. Connected GPS was not always there for early Fitbit models (AFAIK) and it takes a while for the user to establish such connection. Then Ionic came up with built-in GPS but probably majority of users rely on automatic walk/run detection which doesn't use GPS at all. Looking further, if GPS-enabled activity would count distance using GPS then there would be no consistency in the daily distance which would be a mix between stride-based distance and GPS-based. So I think Fitbit decided to keep things old way, from "before GPS" times, and make distance using stride and steps only even for modern devices. It's just a guess but considering that Fitbit devices are not really GPS watches (and Ionic, the only one with built-in GPS has issues with this particular feature) then the distance is poorly estimated and will never be accurate for step-based activities. If you use AppleWatch or any GPS sports watch like Garmin or Polar, then they work differently. They use GPS to measure all running parameters like distance, pace, speed etc. It's something that could be fixed but if there was any will of doing it Fitbit would do it long time ago. Interesting thing is that cycling computes distance using GPS which makes it more accurate (there are no steps to use for that purpose). One more thing is that Ionic doesn't stop increasing distance when the GPS connection is lost (you can see it in the TCX file). Competitors' devices don't update the data until the connection is back and the correction is made with use of last known waypoints usually in straght line but GPS blackouts are very short which makes such adjustment accurate enough. This is still more accurate then using steps and stride, especially for long distance runs with variety of surfaces and terrain. Fitbit made weird decision, stuck to it and it made potentially good device inferior to the competitors when it comes to serious training.

[heeemz]

@t.parker thanks, very good explanation. And it does sounds like FITBIT is much more inferior compare to competitor when these feature. One can call those as core sports watch feature, but some of those sporting activities are also very important for fitness and so on, isn't that the domain FITBIT is positioning itself?

BTW - I always use manual exercise mode to ensure it uses GPS based calculation, I do not rely on auto tracking. I hope FITBIT looks at some of these basic requirements for FITNESS / SMART / SPORTS watch or whatever they may want to call as...

[MarioDings]

It’s not (only) an Ionic issue. I have a versa and since a few months it can’t count distance (and speed) its ridiculous. I have a self made tracker running on my versa and that has no problems.

[jmattwood]

I  do the same distance walking on a treadmill 7 days a week, same duration each day. Same speed. Same number of steps (10300), within a dozen either side. Some days, FitBit will calculate the distance which will match that shown on the treadmill (a figure which is the same every day), other days it will show 20-30% more than the treadmill. 

I have my stride length set manually to match the distance shown on my treadmill divided by the 10300 steps I take.

I find the days it calculates reasonably accurately, will follow days where I have also used GPS to track an outdoor walk. Whether there is a correlation or not, I do not know.