Active calorie differences.

I've noticed on my Instinct 2 that if I complete 18 to 20 thousand steps in a normal day it will credit me with 800 to 950 active calories. If however the same amount of steps are done in one as a recorded activity then active calories range from 575 to around 700. I realise it's meant to be an estimate but not, it seems, a very consistent one.

Other watches credit more (probably too much) but are at least consistent.