<prompt> Human: Im 18 yo currently in college and got approved for a discover it student card with a 1000 line of credit. I should be receiving it in a couple days.I was wondering how much should I be spending on the card. I hear that spending too much can hurt your score I was wondering why? I will mostly use it for gas and groceries. Also, should I just use this card for now on and forget about my debit. Of course be responsible and only spend on what I have in my checking.  <response>: So with a 1000 dollar limit you dont have to worry much about debt-to-income ratio. Keep your utilization under 30 300 dollars and youll be fine. As for score calculation, no one knows exactly why. Its some fantasy formula that supposedly assesses the risk of lending to a person. 