The largest factor in your credit score is your pay history (makes up 35%) and surprisingly to many the next largest is your availability (30%). The availability factor in your score isnt based on the $ amount available, rather the percent available. Someone with only a $100 credit card with zero balance will have 100% available, the same as someone with a $1,000 credit card w/zero balance. The less your available (%), the lower your credit score. This is a huge part because the scoring modules look at someone who spends to their max capacity as a larger risk than one who does not abuse their available lines. A person who is living in the 0-10% available area is generally living on inflated income. 1% available can equal as much as 1 point on your score. Other factors in your score are how long you've had credit open, and how many major credit cards (Visa, MasterCard) you have. If you have 5, that's about perfect. These factors only make up 5-10% of your score though. In most cases, I recommend to people never to close their credit cards... unless they have an annual fee. It sounds like this is your first ever credit card, so it likely will drop your score a bit by replacing the card with another with the same limit, but I'd recommend doing that, unless you're ready to make a major credit transaction. In my job I've seen close to a million credit reports. None are the same, but if you have on time pay history over the last 3+ years and 80% + available on your credit cards you're likely going to be over a 700 credit score and going to have no problem getting very good rates and credit when needed.