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How long will this balance take to clear?
Enter the balance, the card's annual percentage rate and the fixed amount you can pay each month. The calculator estimates the monthly interest charge, the number of months to zero and the total interest cost, assuming no new charges are added.
Fixed APR, no new charges, payment above the monthly interest. A low payment does not converge. Estimate only, not financial advice.
Why payoff length is a logarithm
With a fixed payment above the monthly interest, the balance shrinks by a roughly constant percentage each month. That geometric decay can be inverted with a logarithm, which is why the calculator can return a payoff length in months without simulating every statement.
The monthly rate is the APR divided by twelve hundred. The term inside the logarithm must stay positive: if the payment only covers the interest, the balance never falls, and if it is smaller, the debt grows. A payment that exactly equals the monthly interest leaves the balance flat forever. In those cases the formula has no meaningful answer.
What the interest really costs
Total paid is the fixed payment multiplied by the number of months; interest paid is that total minus the original balance. Early payments are mostly interest, so the balance falls slowly at first and faster later. A payment barely above the monthly interest can take decades and cost more in interest than the original debt.
The payment-to-interest ratio makes that trap visible. A ratio close to one means almost the whole payment is consumed by interest each month. Raising the payment shortens the schedule and cuts total interest, often by more than the extra money itself.
Assumptions and failure cases
The model assumes no new charges, a fixed APR and a level payment until the balance reaches zero. Real cards have variable rates, promotional periods, annual fees, late charges and minimum payments that fall as the balance declines. Any new purchase restarts the clock.
If the payment is too low, the result is not a long payoff but no payoff at all, so the outputs should be read with that limit in mind. Treat the months and interest figures as estimates and not as a repayment plan or financial advice; a balance transfer or a call to a nonprofit credit counselor may change the picture.
Frequently asked questions
Why does the calculator show a dash instead of months?
The payment does not exceed the monthly interest charge, so the balance never reaches zero and no finite payoff period exists.
Does it include annual fees or late charges?
No. Only the balance, APR and fixed payment are modelled. Fees and penalty rates would extend the schedule and raise the interest cost.
Should I enter the APR or the monthly rate?
Enter the APR as quoted on the statement. The calculator divides it by twelve hundred to get the monthly rate used in the formula.
Is paying the minimum enough?
Minimums are often set near the monthly interest, which can stretch repayment for years. Compare the result with a larger fixed payment to see the difference.