Debt Payoff Calculator
Find how long to clear a debt and the total interest paid.
Result
Results are estimates for general information only and are not professional advice.
What this debt payoff calculator does
It answers the two questions that matter about any fixed debt: when will it be gone, and what will it have cost. Balances carry a monthly interest charge, so every month the debt survives adds to the total — which means the payment size and the payoff date are far more tightly linked than most people expect.
The formula behind it
The months to payoff are −log(1 − B × r ÷ P) ÷ log(1 + r), where B is the balance, r the monthly interest rate and P the monthly payment. Total interest is simply the sum of all payments minus the original balance. If the payment does not exceed B × r, the debt never clears — the calculator flags this rather than returning an impossible figure.
How to use this calculator
Enter the outstanding balance, the annual interest rate and your monthly payment. The result gives the payoff time in months and the total interest. Compare two or three payment levels: the relationship is not linear, and a 20% larger payment typically cuts far more than 20% from both the time and the cost.
Getting free of it sooner
Direct any windfall — a bonus, a tax refund, a sold item — straight at the principal, where it removes all the future interest that balance would have generated. Keep paying the same amount even as the balance falls, since a payment that shrinks alongside the debt is what stretches repayment out. If you hold several debts, clearing the highest-rate one first is always the cheapest route mathematically.
Frequently Asked Questions
What is the Debt Payoff Calculator?
Find how long to clear a debt and the total interest paid. It runs instantly in your browser and is completely free to use.
What do I need to enter to use the Debt Payoff Calculator?
The Debt Payoff Calculator asks for the following values (3): Debt balance, Annual rate (%), Monthly payment. Fill them in and the result appears immediately — the calculation runs on your own device, so nothing you type is sent to a server.
How accurate is the Debt Payoff Calculator?
The Debt Payoff Calculator uses standard, widely-accepted formulas, so its figures are reliable estimates for everyday planning. They are not a substitute for advice from a qualified professional.
Is the Debt Payoff Calculator free, and do I need an account?
Yes. The Debt Payoff Calculator — and every other calculator on Calculatis — is completely free, with no registration, no download and no limit on how often you use it.