Innaccurate stairs count

[Hammerojustice]

What is going on with my Fit bit One?  When I woke up, I had zero steps & stairs as it should have been.  I walked to and from my bathroom a few times which is on the same floor and off my bedroom, so I wasn't surprised at the step count (~160), but I was extremely surprised I was listed as having done 6 flights of stairs while only walking to & from my bathroom.  What's going on???

[Doug]

The way fitness trackers compute "stairs" is by inferring elevation from changes in atmospheric pressure.  All else being equal, air pressure decreases as elevation increases.  The difference in air pressure is used in impute changes in height, with each ten foot of perceived elevation increase being granted one flight of stairs.  (This is an oversimplification, as there are other factors to help exclude elevation changes from riding an elevator or airplane for example.)

The catch here is "all else being equal".  The process generally works quite well when air pressure is not changing for other reasons.  Possibly the most common of these is weather patterns.  If you have a low pressure area rolling in and are outdoors (or have windows open) the air pressure can be dropping while you are at the same elevation.  If you are walking around when that happens, it can end up being construed as elevation changes and input "stairs".

Some people have also reported earning "stairs" while walking outdoors when there are variable and shifting wind directions.  It seems as if the variable flow of air across the air pressure sensor can sometimes fool it into imputing "stairs" too.  In my 4.5 years of using a Fitbit One, that has rarely happened to me personally.  

So if you "earned" six flights of stairs walking to & from your bathroom, I'm going to go out on a limb here and guess your windows were open and there is a low pressure area moving in.  Or maybe you had some fans on and your movements exposed the air sensor hole on the back of the One to just the right conditions to appear the air pressure was dropping while you walked.

[fiftyeight]

I had an instance last week of my One not counting floors that I knew I had done!  What could've caused that?

[Doug]

A common misconception is that a residential flight of stairs should be counted.  But in most homes, you typically have closer to 9 feet of elevation change.  And often less for basement stairs.  The One is calibrated to infer one flight of stairs per 10 feet of elevation rise.  Thus you typically do not quite earn a flight of stairs from a single residential stairway.  Depending on how close your stairway comes, you may be able to get them counted if you either do a deep-knee bend before starting to go up the stairs, or I've heard of people who keep a chair or stool at the top of the stairs then climb on that to reach the 10' elevation rise.

Another common misconception is that you can do repeated trips on a short flight of stairs and they will accumulate to multiple sets of 10'.  However this does not work either because once you start going back down, the 10' minimum rise resets and you are starting all over.  So you CANNOT do repeated instances of short flight (say a deck or split-foyer half flight).  Or a stepper or continuous stair machine at a gym.  You'd get as much physical benefit, but without the actual rise change in air pressure due to the elevation change being at least 10' in a single direction, the One will not credit you with the effort.

If you were walking up flights of stairs over 10 feet, or any incline such as hilly terrain or parking ramp or similar, then I don't know what would have caused it.

[fiftyeight]

Doug, I was in hilly terrain!  Puzzling!  Thanks anyway, for your reply.