How low should I keep my credit card balance while building a brand-new U.S. score?

Aim to keep your reported credit utilization well below 30% of your limit, and ideally under 10%, because utilization is one of the biggest scoring factors and matters a lot when your file is thin. On a new secured card with a low limit, even normal spending can spike utilization, so consider paying the balance down before the statement closes, not just by the due date, since the statement balance is what usually gets reported. Never carry a balance for 'credit-building' reasons; paying interest doesn't help your score. Consistent low utilization plus on-time payments builds a solid score in months. Model it with the Utilization Optimizer at wealthserene.com/tools/utilization-optimizer, and the CFPB covers utilization at consumerfinance.gov.