How about a best guess with a bit of educated reading behind it

I've been at this for a couple of years so while it sound like a lot of research, it's actually been spread over time. I've fool with my fitday.com account. I've studied other online calculators. I've taken a weightloss and figured backward from there. I've taken a 'stand still' amount of calorie intake and figured my expenditures must be the same then.
It's very individual and not very scientific but it's good enough for me to work with. Did that make sense?