Depends on what strain you grow and how powerful your light system is. Thats a question alot of people ask but no one can awnser for you. With a high yeilding plant like K2 if you use a 1000watt HPS light you can get between one and two pounds. But thats if you have nice equipment. You may get anywhere from 15 to 30 grams if your doing it on the cheap. Light is the most important thing. It makes all the difference. But its not the only important thing. If you got the cash I can help you get started grow good plants because I've got a system here for sale. http://boards.cannabis.com/showthread.php?t=40336 That there is a typical light setup.