Utilization is the share of your available credit you're using — balances divided by limits. It's one of the largest factors in most credit scores, second only to payment history.

You'll often hear "keep it under 30%." That's a useful rule of thumb, not a magic line; lower is generally better, and the figure that matters is what's reported on your statement date, which may differ from your day-to-day balance.

Two easy levers: pay down balances before the statement closes, and avoid closing old cards, since that shrinks your total limit and can push utilization up.