how many calories should i eat to maintain my weight? help!

hi,

i'm 6'1, 154lbs, and 19 year-old male.

i usually consume about 2500calories a day (mostly healthy food).

i do weight training about 50 min and a run on a treadmill for about 20 min everyday.

my goal is to gain like a pound or two muscle wise.( i still would like to lose the last bit of my belly fat, tho)

how many calories would i need in order to achieve my goal?

also, somedays, i just lose control, dont count the calories and consume about 3500, is it really bad for me?

thanks.

Try entering your stats into this weblink which is designed for people under 20.  http://www.kidsnutrition.org/bodycomp/bmiz2.h tml  With activity of about an hour a day you should then read off the 'moderate' daily energy requirement.... 3400.  So your 2500 is keeping you at a very low weight and your 3500 'out of control' days are a lot nearer the mark.  It's unlikely you have belly-fat, it's probably just loose skin.

If your 'healthy food' is food that is low-calorie but high bulk such as diet products and fresh vegetables, try to swap some of your choices for higher-calorie, low-bulk foods such as oils, red meats, nuts & nut butters, avocados, dried fruit...  And try to eat 'little and often', a meal or a snack every two hours. 

If you want to gain weight you'd have to be looking at 4000 cals a day minimum.

with your age, height, weight, and activity level you should be eating 3k calories just to maintain your weight.