I've had really good luck with my calculations in the past. My activity level is probably seated with some movement, but I set it as seated all day to be more conservative in the estimate. I've hit my goals in time or early by following the recommendations, or even having a smaller calorie deficit than fitday recommends. For example, I gave myself a month to lose 7 pounds before a cruise last October, and by using fitday, I hit my goal the day before I left for my trip. I'm using it right now to hit vacation weight once again, and so far, I'm ahead of schedule.