Utilization at a low percentage on your cards is what increases your score. Keeping it below 10% gives you an excellent rating for that card. These card companies make money by skimming pennies off every transaction you make. Sure interest makes money but it makes it at a higher risk, they want low risk consistent income you keeping a low Utilization tells them that according to the risk profile. You can literally open a card never use it and keep it open and your score will go up over time from "on time payments" a higher total credit limit with low Utilization and a longer credit age as that card ages.