The Harris-Benedict equation tries to find your maintenance calories, first by a series of variables to determine your basal metabolic rate (the calories you burn at bed rest (doing absolutely nothing but surviving)) and then multiplying it by a number based on your activity level.

For Men:
BMR= 66 + (13.7 x bw in kg) + (5 x height in cm) - (6.8 x age in years)

For Women:
BMR=655 + (9.6 x bw in kg) + (1.8 x height in cm) - (4.7 x age in years)

after you discover your BMR, take that number and multiply it by one of these figures based on your activity level:

Sedentary= x1.2
Lightly Active= x1.375
Moderately Active= x1.55
Very Active= x1.725
Extremely Active= x1.9

add 500 calories to bulk

1g of protein per lb of bw
0.5g's of fat per lb of bw
carbs make up the rest