Mileage Calculations

[GGinPA]

Starting at the beginning of December, half of my Miles stats are much lower than they should be, sometimes off by more than 50%. For example, my stats for 12/10-12/13 (my stride is 2.5 feet or 2112 steps/mile)

12/10: 10771 steps, 5.05 miles (this is accurate)

12/11  9151 steps, 3.66 miles (this should be 4.33 miles)

12/12  9083 steps, 3.37 miles (this should be 4.30 miles)

12/13  9693 steps, 2.22 miles (this should be 4.59 miles)

It is obvious that an error has been introduced into the algorithm used to make the calculation in the app.

[MrMarv]

@GGinPA -

My first thought after looking at the first three days was that possibly you took a long, leisurely GPS assisted walk on days 2 and 3 where the mileage was calculated by GPS instead of steps * stride length and with the walks being leisurely, the stride length would be shorter. Maybe even to the tune of 25 and 23 inch stride length instead of 30, especially since GPS, while pretty decent most of the time, is sometimes really off. Occasionally my walks show me walking through the next door neighbor's backyard pool or another's kitchen.

But then day four came along and just blew that up, didn't it? A 14.5 inch average stride length for the day? I don't think so.

What device do you have and have you taken a firmware update to that device in the last month? And is your app on iOS or Android?

While I haven't experienced anything like this, maybe someone else has and can shed some light on the issue.

Good luck.

[GGinPA]

My Android app reports that my Versa is up to date.
Most of my steps are done on a treadmill in my home. I use a consistent
speed that is set to keep my pulse at the optimum level, typically for
about 90 minutes. The treadmill's mileage stats jibe very closely with the
Fitbit when the Fitbit computes the distance correctly.
It is strange that the errors are occuring about every second day.

[MrMarv]

@GGinPA -

This may be a reach, but I have seen it happen before...

First off, is your stride length firmly set in the app or is it allowed to be dynamically calculated?

In case you don't know how to check it, in the iOS app - hopefully the same in the Android app:

• Tap your account icon at the top left of the screen
• Scroll down the account page and tap "Activity & Wellness"
• Tap "Exercise"
• Scroll down past all of the auto-recognized exercises and tap "Stride Length"
• There you will see if "Set Automatically" is turned on and what the calculated stride length is.
• If it it not turned on, then the stride length is fixed.

If it is dynamically calculated, then that could be the culprit. I'd recommend routinely checking it before and after each treadmill session for a while.

I have a fixed stride length and my treadmill sessions measurements are consistent with that 30 inch step. I just verified two weeks worth of two-a-days on the treadmill and they all range between 29.6 and 30.1 which is understandable with miles being rounded to two decimal places and steps not being rounded at all. The .5 is just a product of the miles not being "exact".

My .5 difference isn't anything like your 15.5.

The other thing is that I have found the exercise apps on FitBit devices have quite a few "quirks", aka "bugs". Heart rate reporting is one. I routinely have my heart rate overstated by 10 - 20 bpm when using the treadmill app on my Versa 2, and have documented a five-minute sustained over 140 bpm peaking at 156 (which is nearly impossible with the medications I am taking and my implanted defibrillator didn't kick in) when a manual measurement and pulse oximeter reading showed high 90s. And yet, another day will vary less than 10 bpm for the whole hour I'm on the treadmill.

Go figure.

Sorry I didn't have anything definite to share.

Good luck.