Inspire 2 not crediting me with enough miles

[Pthep]

I walked today on a route carefully calibrated with mile markers,  and ran Runkeeper along with my Inspire 2, to give me my pace along with the Fitbit's steps, distance, heart rate, etc.    Runkeeper tallied my walk at 18.40 miles, which almost exactly matched the distance on the mile markers.   But the Fitbit  marked me at 17.52 miles -- including some walking around before I started the Runkeeper -- so that's more than a mile too short.   This also happened to me last year at the Sierra Club's annual 50k hike, calibrated exactly, when the Fitbit marked me at something like 27 miles instead of the actual 31. 
       Could the shortage result from inaccurate settings for my stride?  I thought it was actually calculating the distance with GPS.   In any case, how can I make it show the proper distances for my walks?  These are pretty significant discrepancies.  --- Pat M.

[Julia_G]

Hi, @Pthep the Inspire 2 will either use the GPS on your phone to calculate your distance (Fitbit “connected GPS”) or, if your Fitbit does not connect to GPS, or if it loses connection during the period of your walk or run, then it will use your stride length instead to calculate your distance (distance = stride length X number of steps).  The stride length X steps calculation is always likely to be less accurate than a GPS calculation, because, of course, no ones stride length is exactly consistent over all varying terrains, and there are also can be an approximate 5% either way error factor in step counting (so each 100 real steps could be counted as 95-105.  Over 18 miles even a 5% error factor could add up!)

For most accuracy I would recommend using the connected GPS feature, manually starting your activity using the Fitbit app and making sure that GPS successfully connects.

Impressive step count and run, by the way!

[Pthep]

Thanks for your response.
But I don't even see a way, with the current app (and lack of a computer
dashboard), to tell them what my stride is. Am I missing something?
It's also unlikely, since this whole trail was in the very populous D.C.
suburbs, that it would have lost the GPS signal, so that adds to the
mystery.
But anyway, if I CAN adjust my stride length -- maybe it sees that
because I'm a little old lady (66 years old and short), it figures I'm
not covering much ground -- I would. If I could give a more accurate
figure, I'd like to do that. How?