How Credit Card Interest Works
I built this calculator to make the true cost of carrying a credit card balance visible. Credit card interest compounds daily in most cases — your annual percentage rate (APR) is divided by 365 to get a daily rate, which is applied to your balance each day. That means even a month of carrying a balance costs more than a simple fraction of the APR would suggest.
Enter your current balance, APR, and monthly payment to see how long it will take to pay off the card and how much total interest you will pay. Raising your monthly payment by even a modest amount can dramatically shorten the payoff timeline and cut interest costs.
Minimum Payments: Why They Are Expensive
Card issuers typically set minimum payments at a small percentage of the outstanding balance, often around 1–2% plus accrued interest and fees. Paying only the minimum keeps the balance high for a very long time and means a large portion of each payment goes toward interest rather than principal.
- APR: Annual Percentage Rate — the yearly interest rate on your balance. Divide by 12 to approximate your monthly interest charge.
- Minimum payment trap: Paying only the minimum on a large balance can stretch repayment over many years and multiply the total cost.
- Fixed monthly payment: Committing to a fixed payment that is higher than the minimum accelerates payoff and reduces total interest significantly.
- 0% intro APR offers: Useful for consolidating debt, but be aware of the rate that kicks in after the promotional period ends.
Strategies to Pay Off Credit Card Debt Faster
Use this calculator to model different scenarios before committing to a strategy. If you have multiple cards, the debt avalanche method (paying minimums on all cards, then directing extra money to the highest-APR card) minimizes total interest paid. The debt snowball method (targeting the lowest-balance card first) provides psychological momentum through quicker wins.
Another option worth modeling is a balance transfer to a card with a 0% promotional APR. If you can pay off the transferred balance within the promotional period and the transfer fee is less than the interest you would have paid, it is often a net win.
Frequently Asked Questions
How is credit card interest calculated each month?
Most issuers calculate interest using the average daily balance method. They add up your balance at the end of each day in the billing cycle, divide by the number of days, and apply the monthly periodic rate (APR divided by 12) to that average. The result is the interest charge that appears on your statement.
Does paying more than the minimum hurt my credit score?
No — paying more than the minimum never hurts your credit score. In fact, reducing your balance lowers your credit utilization ratio, which is one of the most significant factors in your score. Keeping utilization below 30% of your available credit is generally recommended.
What happens if I miss a payment?
Missing a payment typically triggers a late fee and may cause your issuer to apply a penalty APR, which is often significantly higher than your standard rate. Payments more than 30 days late can also be reported to credit bureaus and negatively impact your credit score. If you miss a payment by accident, call your issuer — many will waive the first late fee as a courtesy.