get your bmr, multiply it by an activity factor (1.5-2.0, probualy closer to 2.0 dependingon activity, if you were bed ridden in the hospital you would likely have an activity factor of 1.2) then add your 500. however, adding 500 cals is probualy way to much, unless you are extremely tall and skinny. or if you are on a cycle. adding 500 cals is gaining 1 pound of weight per week, do you really think you can put on that much weight of MUSCLE that fast? i would cut that in half or a fourth. but then again it all depends on your situation