A credit card balance can take years to clear when the payment is only a little more than the interest. Putting the balance, rate and payment into one calculation gives you a payoff month to aim for and shows what an extra $50 or $150 a month actually buys you in time and interest.
How the debt payoff formula works
Card issuers usually charge interest on your average daily balance. The calculator uses a simpler monthly model: it divides the APR by 12 and applies that rate to the balance each month. At 19.9% APR that is about 1.66% a month, or $199 of interest on a $12,000 balance in the first month.
Your payment covers that interest first, and whatever is left reduces the balance. Next month's interest is then a little smaller, so a little more of the same payment goes to principal. The formula above solves for n, the number of months, from the balance B, the monthly rate r and the payment M. It also explains why a payment barely above the interest stretches payoff out for years.
Worked example: paying off a $12,000 balance
For example, imagine you have a $12,000 credit card balance at a 19.9% annual percentage rate. If you make a steady $350 monthly payment with no extra contributions, it will take 52 months to pay off. Over that time, you will pay $5,889.43 in total interest, making your total amount paid $17,889.43.
Add $50 a month, bringing the payment to $400, your payoff time drops to 42 months, saving you $1,152.91 in interest. If you can afford an extra $150 a month (a $500 total payment), you will be debt-free in just 31 months, saving $2,460.95 in total interest compared to the base payment.
How to use the result
Start from the date you want to be debt-free and adjust the payment until the result lands there. The calculator handles one balance at a time, so with several debts, run each one separately. Paying the highest rate first saves the most interest; paying the smallest balance first clears accounts sooner. Either way, keep your payment steady as the balance falls. Card minimums usually shrink with the balance, and following them down is what stretches payoff out.
Limits and assumptions
This calculator assumes a fixed interest rate, a constant monthly payment, and that you do not add any new charges to the balance. In reality, credit card interest rates are often variable, and continuing to use the card will reset your progress. It also requires your payment to exceed the monthly interest charge; otherwise, the debt will never be paid off. Treat the result as a plan to test, not a promise. If a lower-rate personal loan could replace the balance, compare its payment with the loan calculator, and once the debt is gone, the compound interest calculator shows what the same payment could grow to.
Key terms
- Principal balance
- The total amount of debt you currently owe, before future interest is applied.
- Annual percentage rate
- The yearly interest rate charged on your borrowed balance, often referred to as APR.
- Minimum payment
- The smallest amount you are required to pay each month to keep your account in good standing.
- Extra payment
- Any additional money paid above your planned monthly payment, which goes directly toward reducing the principal.
- Payoff date
- The estimated month and year when your debt balance will finally reach zero.