It is covered here:

http://www.myfitnesspal.com/topics/show/819055-setting-your-calorie-and-macro-targets

Relevant extract:

"There are many TDEE calculators available on the interwebz. A couple of good ones are:

http://www.exrx.net/Calculators/CalRequire.html
http://scoobysworkshop.com/calorie-calculator/ (but ignore the rest of the site as it's full of bs).

Note however, these are all estimates of averages. The best determination of what your TDEE are your results. If you have been tracking for a while, you should be able to look back over a period of time and calculate what YOUR actual TDEE is. For example, say I lost 8lb over a 10 week period while eating an average of 2,000 calories a day. My TDEE would be: 2,000 x 7 days x 10 weeks (140,000) which represents the total calories consumed over the 10 week period plus 8 x 3,500 (28,000) which represents my weight loss expressed as a deficit using the 3,500 calories per pound approximation. My total expenditure over that period would be 168,000 (the 140,000 plus the 28,000) divided by 70 (7 days x 10 weeks) = 2,400 per day. This would approximate my TDEE. Obviously this number should be tweaked up or down if there is any significant change in activity. It also assumes that you have been logging your intake accurately."

One week is not long enough, but assuming the 2lb loss is an accurate representation of 'real' losses (i.e. not water.food weight) then your calculations include exercise.

What happens if over the time frame rather than losing weight you gained one pound? Would you instead subtract 3500 calories from the amount consumed before dividing it by the number of days? Thanks!