How does the app calculate mileage

[SunsetRunner]

Yesterday I did three walks 8.54 miles, 9.08 miles, and 4.66 miles. I'm going to say I believe those values to be accurate (or close enough)  The app said I had 30.83 miles. I didn't just sit still during the time's I wasn't tracking a walk, but there is no way I walked an additional 8.55 miles.  I did a test today. I had 11.73 miles. and I tracked a walk of 1.07 miles.  The app said I had 13.1 miles.

I can see it using my steps to estimate a distance if I am not tracking the walk, but if I track a walk, I expect it to use the tracked distance when adding to my daily mileage.

Does anyone know what the app is doing?

If it is just using steps to calculate my daily distance, can it be changed to use the tracked distance?

[JohnnyRow]

Are you using GPS for any of this?

If not, distance = number of steps times stride length.

[SunsetRunner]

This is going to sound stupid, but I don't know. My phone updated to Android Pie and the location options have changed. I'm going to say that I am because Google Maps used to prompt me  to switch to "High Accuracy" when I was on "Battery Saver", and it doesn't do that now. In the midst of my walks, when I look at Google Maps, it tracks my location. 

I have the ability to add Bluetooth and WiFi to increase the accuracy, but I don't see how that would change my issue (but not understanding how it works exactly, maybe it would).

The issue I am looking at seems as though the daily mileage tracker and individual walk tracker are two separate things that don't talk to each other (like weather apps where the daily and hourly forecasts don't agree with each other). The mileage I ended with was not the sum of the mileage I started with, and the distance of my walk. It's like the walk tracker is using the GPS and the daily tracker is using steps.

[JohnnyRow]

Which tracker do you have?

Do you get a map with the workout summary?  If so,. it is using GPS.

[SunsetRunner]

I'm using MobileTrack.

I am getting the maps.

[JohnnyRow]

I see, Mobile Track.  Sorry, I don't have much knowledge of how that does things.

Your explanation guess seems plausible but I really just don't know.

[Colinm39]

@SunsetRunner  Here is the link to Mobile Track. help text.  It's important you have a measured stride and many of us did that by walking around an athletic track which gives you some distance and averages the stride at walking pace..   I'm fortunate where I live that I have a straight level street, and all of the house block frontages are 15.24m (50').

Also in my testing I found that Fitbit varies the stride it's using if it detects your speed of moving drifts into a running speed and distance can vary because of that..

Extracted from the Mobile Track text

How does MobileTrack track distance?

Your distance is estimated by your stride length. By default, stride length is calculated using your height and sex. If you feel that your distance estimate isn't accurate, you can adjust your stride length by following the instructions in How do I measure my stride length ?.

Default stride is Men = Height x 0.415 and Women = Height x 0.413

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@SunsetRunner wrote:

I'm using MobileTrack.

I am getting the maps.

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[SunsetRunner]

Colin,

Thanks for the information.  I probably should check my stride at a point.

I still have the issue that (and I'm just putting numbers in here because I can't see my prior posts the way I came into this)  I started my walk with 7 miles for the day. I tracked my walk for 1 mile. My daily miles say 8.5 miles. 

I'm guessing it ignores the tracked data, and just uses stride for the daily calculation.  I'm just trying to get verification/clarification of that. 

[Colinm39]

@SunsetRunner  I was just answering a similar post about the GPS ability to track at this link and I posted this para..  But in the link he states that the stride is used to calculate distance and the moderator is involved.. So maybe we get a response..  This was GPS not MobileTrack

When I test some of these theories I use the Activity Record option in the PC Activity log which is a copy of your actual data and graphed every minute.. Non destructive  and you get the image below which is a minute x minute analysis. You can also edit this type of activity... I was doing this to compare the Fitbit One, Zip and my HR trackers and found that on a deliberate walk, no idling I was within 3% of the step count with all trackers.. The times when I was domestic, I was missing about 10-15% steps on a HR model, but compensated with the calorie burn because of the HR recording.

Back calculating this, it calculated my stride at 79.55 and it's set at 80cm, so allowing for Fitbit not using 3 decimal points for metric it's probably spot on..because Fitbit tend to round down and in this case the stride a steps =0.794.4

Fitbit have stated in this community that the calculation they use to determine default stride lengths is proprietary and cannot be disclosed. However, others have reverse engineered their own data and come to a conclusion that the default walking stride is 0.415 x height for men and 0.413 x height for women.

[Colinm39]

@SunsetRunner   You can use the Activity Record to examine segments of your walking and back calculate what Fitbit sees as your stride..  Keep in mind its non-destructive and only a copy of your data and editable via the edit pencil.

[RicardoFitbit]

Hello guys! I'm happy to see you posting in our Community Forums again @SunsetRunner @JohnnyRow @Colinm39, It's a pleasure to assist. My apologies for the delayed reply.

@SunsetRunner  Let me share with you that, as previously mentioned, your distance is estimated by your stride length. By default, the stride length is calculated using your height and sex, therefore, this information will be specific for every user. If you feel that your distance estimate isn't accurate, you can adjust your stride length by following the instructions in: How do I measure and adjust my stride length? and let me know how it goes? For more information and details I recommend you to check: How do I use MobileTrack?.   

@JohnnyRow @Colinm39 thanks for your replies and suggestions, it's always nice seeing both of you helping other users here in the Community. 

Let me know if you have any additional questions, I'll be around.