It's a valid question - how many calories do you need each day?
The answer varies on your goals and other variables. Are you trying to lose weight? Maintain weight? Are you actively burning calories each day? How many?
Matt Fitzgerald's post on www.active.com provides some insight on strategies as well as some calorie counting tools to make the right decisions based on your goals.
Generally speaking - you want to take in less calories than you burn off. That theory has some variables, however.