How Does Credit Card Interest Work and Why Do Balances Grow?

Short answer: Card interest is charged daily on the balance you carry past the due date. Because unpaid interest is added to the balance, it compounds, and minimum payments mostly cover interest at first. That's why a balance can feel stuck even when you pay every month.

How interest is calculated

1. Your APR is divided by 365 to get a daily rate (22% APR is about 0.06% a day).
2. Each day's balance is multiplied by that rate.
3. The month's interest is added to your balance.

If you pay the full statement balance by the due date, most cards charge no interest on purchases. That grace period disappears once you carry a balance.

Why people end up with card debt

The Federal Reserve's household well-being survey consistently finds that a large share of adults couldn't cover a modest emergency expense with cash. Common triggers include:

• medical bills or car repairs,
• a drop in income,
• everyday costs rising faster than pay,
• using cards to bridge short gaps that become long ones.

Minimum payments

Your statement must show how long paying only the minimum will take and the total cost. The CFPB's card tools explain these disclosures. A minimum of 1%–3% of the balance plus interest can stretch payoff over many years.

Credit card debt and your credit score

Credit utilization, the share of your available credit you're using, is one of the biggest factors in most scores. Paying balances down usually helps your score.

Sources

• CFPB, Credit cards
• Federal Reserve, G.19 Consumer Credit release
• Federal Reserve, Economic Well-Being of U.S. Households (SHED)

Last reviewed October 12, 2026. This article is general information, not legal, tax or financial advice.