I figured out my average per day being around 70 km/day (I enjoy doing off road stuff). I use that figure out places to stay, quantity of food/water need etc. However when I make a time frame for the purpose of booking a flight on a long trip, I use 60 km/day (6 days riding with 1 day off/week, 420 km/week) plus the number of days I want to spend being a tourist in an area. Works pretty good for me.