Debt Payoff Calculator
This calculator estimates how many months it will take to pay off a debt given its current balance, interest rate, and a fixed monthly payment, along with the total interest you’ll pay over that time.
The Formula
Each month, interest accrues on the remaining balance at the monthly rate (APR ÷ 12), and your payment is applied after that interest is added. The simulation repeats until the balance reaches zero, summing total interest paid along the way.
Note: If your payment doesn’t exceed the monthly interest charge, the balance will never shrink; this tool is for general educational and planning purposes only.
Last reviewed August 2026