What is debt-to-credit-limit ratio?

It is a ratio between the credit limit on an account vs what you actually owe on the account.

If you have a credit card with a $10,000 limit on it and you currently owe $3,500 on it, your debt-to-credit-limit ratio would be 35% ($3,500 is 35% of $10,000).

Typically, you want to keep this percentage under about 30%.