APR stands for Annual Percentage Rate. It’s the yearly cost of borrowing money, expressed as a percentage of the outstanding balance. When a credit card says “24.99% APR,” that means if you carry a $1,000 balance for a full year, you’ll pay roughly $250 in interest — though the actual calculation is slightly more complex because interest compounds.
Most credit cards compound interest daily. The daily periodic rate is your APR divided by 365. A 24.99% APR works out to roughly 0.0685% per day. On a $1,000 balance, that’s $0.69 of interest added every single day. After a year, because that interest also compounds, the effective annual rate (EAR) ends up slightly above 28%.
The key practical insight: carrying a credit card balance is extraordinarily expensive. At 20% APR, a $5,000 balance costs you $1,000 per year in interest — money that disappears and builds zero equity or value. Every dollar you put toward that balance saves you that same rate in interest, every year, until the debt is gone.
Lower-rate debt like mortgages (typically 3–7% APR) and federal student loans (4–8%) behaves very differently. Because the interest cost is much smaller relative to the balance, aggressive early payoff is more of a personal preference than a math-driven necessity. High-interest consumer debt (credit cards, payday loans, buy-now-pay-later) is a different story — the rates grow fast enough that paying it down quickly is almost always the right move.