A credit utilization ratio is used in the calculation of credit scores. It compares the amount of credit being used to the total credit available to the borrower. Having a low ratio — in other words, not much debt but a lot of available credit — is good for your credit score. Experts say you should keep that ratio as low as possible, both overall, and on each card . The ratio is also known as a balance-to-limit ratio, or credit-available-to-credit-used ratio.