Credit Card Calculator
See how long it takes to pay off a credit card balance and how much total interest you'll pay — for any combination of balance, APR and monthly payment.
How to use the Credit Card Calculator
- Enter your inputs into the Credit Card Calculator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
The credit card payoff formula
n = −log(1 − P·r/M) / log(1 + r)
P is the balance, r is the monthly periodic rate (APR / 12), M is the fixed monthly payment. The result n is the number of months until payoff. Total interest = M × n − P.
Worked example
A $6,000 balance at 21% APR with $150/month payments: n ≈ 65 months (5.5 years). Total interest paid: about $3,750. Increasing payment to $300/month cuts payoff to 24 months and interest to about $1,376.
Frequently asked questions
Why do minimum payments take so long?
Minimum payments are typically calculated as 1–3% of the balance plus interest. As the balance falls, the payment falls, dragging out the payoff and inflating total interest dramatically.
What APR am I likely to have?
Average US credit card APR for cards carrying a balance was 21.47% in early 2026 — near a multi-decade high. Rates can range from 0% promotional to 30%+ for store and subprime cards.
Should I use a balance transfer card?
A 0% promotional balance transfer with a 3–5% transfer fee can save money if you clear the balance before the promo ends. Run both scenarios in the calculator to compare.