Utilization: the 30% rule

Utilization is the share of your limit you are using. On a $300 limit, a $90 balance is 30% utilization. Below 30% helps; below 10% helps more.

The balance the card reports is usually the one on your statement date, not after you pay. Paying a few days before the statement closes lowers the number the bureaus see.

Utilization has no memory. A high balance last month stops hurting as soon as a lower balance is reported.