Credit Card Calculator
Estimate how long it takes to pay off a credit card balance, and how much interest you'll pay at different payment amounts.
Formula
Interest = Balance × (APR / 12)
Monthly interest is balance times monthly rate. Each payment covers interest first, then reduces principal. Paying only minimums keeps you in debt for years.
Worked Examples
Example 1: Minimum Payment Trap
Problem:$8,000 balance at 22% APR, paying minimum only.
Solution:Minimum payment starts at ~$160 (2% of balance)\nDecreases as balance decreases\n\nTime to payoff: ~25 years\nTotal interest paid: ~$12,000\nTotal paid: ~$20,000\n\nYou pay $2.50 for every $1 borrowed!
Result:25 years, $12,000 interest
Example 2: Fixed Payment Strategy
Problem:$8,000 at 22% APR, fixed $300/month payment.
Solution:Fixed payment: $300/month\n\nTime to payoff: ~35 months (~3 years)\nTotal interest: ~$2,600\nTotal paid: ~$10,600\n\nCompare to minimum payment:\nSaves: ~$9,400 in interest\nSaves: ~22 years!
Result:3 years, $2,600 interest
Example 3: Multiple Cards - Avalanche
Problem:Card A: $5,000 @ 24%, Card B: $3,000 @ 18%. Extra $200/month beyond minimums.
Solution:Card A minimum: $100\nCard B minimum: $60\nTotal available: $360\n\nAvalanche: Pay Card A $260, Card B $60\n(extra $200 → highest rate)\n\nCard A paid in ~24 months\nCard B paid in ~6 more months\nTotal: ~30 months, $1,800 interest\n\nSnowball (smallest first) would take ~32 months, $2,000 interest
Result:Avalanche saves $200
Frequently Asked Questions
How is credit card interest calculated?
Daily periodic rate = APR ÷ 365. Each day, interest = balance × daily rate. These daily charges are summed for your monthly statement. Interest compounds on unpaid balance including previous interest.
What is a good credit card APR?
Excellent credit (750+): 15-20%. Good credit (670-749): 20-24%. Fair credit (580-669): 24-28%. Poor credit: 28%+. Cards for excellent credit may offer 12-15%. 0% intro APR cards available for balance transfers.
What is a credit utilization ratio?
Balance ÷ Credit Limit. Keep below 30% ideally (below 10% is excellent). High utilization hurts credit score. Utilization is calculated both per-card and overall.