It's really not accurate. I've been using it for a few years now and I still can't figure it out.
It's interesting that it seems to calculate floors UP much better than floors DOWN. On a typical day it shows me 7 floors climbed and 3 floors descended. Based on my movement during the average day, these should always be equal or at least closer together. Floor descended are always really low.
By the way, floors up is also never correct.. it shows 7 but this is also wrong. I know it's based on a certain elevation change but regardless it never works right.
It is also based on arm movement while the air pressure changes. If the watch counts more stairs up than down, it could be related to how you move your watch arm on your way down the stairs.
