How many calories should I be eating a day? (Curiousity)?

Hey, I'm 14, Male, 5'8 or 5'9. I'm about 9.5 Stone. about 59kg - 60kg. I'm not that active, I never have anytime, apart from being at school and walking around there. I usually consume around 1800 to 2500. Just out of curiosity how much should I be eating? People say 2000 to 2500 but I'm not sure, thanks :D Not that I'm going to set an amount to eat a day, it's just out of boredom and curiosity.