Debt Payoff Calculator
Estimate how many monthly payments it takes to eliminate a credit card or loan balance given your APR, minimum payment, and any extra amount you can add. Helps you see the dramatic effect of small extra payments on payoff time.
About this calculator
The number of months to pay off a fixed balance with a constant monthly payment is derived by solving the compound-interest balance equation for time. The formula used is: Months = ⌈log(1 + (B × r) / P) / log(1 + r)⌉, where B is the current balance, r is the monthly periodic rate (APR / 100 / 12), and P is the total monthly payment (minimumPayment + extraPayment). The ceiling function ⌈ ⌉ rounds up to the nearest whole payment. This works because each month the balance grows by factor (1 + r) before the payment P is subtracted; solving for when the balance reaches zero yields the logarithmic expression above.
How to use
Suppose you have a $5,000 credit card balance at 20% APR, a $100 minimum payment, and you can add $50 extra. r = 0.20/12 ≈ 0.01667, P = $150. Months = ⌈log(1 + 5,000 × 0.01667 / 150) / log(1 + 0.01667)⌉ = ⌈log(1 + 83.33/150) / log(1.01667)⌉ = ⌈log(1.5556) / 0.007228⌉ = ⌈0.4418 / 0.007228⌉ = ⌈61.1⌉ = 62 months. Without the extra $50, it would take roughly 94 months — 32 months longer.
Frequently asked questions
How much interest do I save by making extra monthly debt payments?
Extra payments reduce the principal faster, which reduces the balance on which interest accrues each subsequent month. Even a modest extra $50 per month on a $5,000 balance at 20% APR can save hundreds of dollars in interest and cut years off repayment. The savings are largest when the interest rate is high and the balance is paid early. Use the calculator to compare your current path against various extra-payment scenarios to find the most affordable acceleration.
What is the difference between the avalanche and snowball debt payoff strategies?
The avalanche method directs extra payments to the highest-APR debt first, minimizing total interest paid across multiple debts — the mathematically optimal approach. The snowball method targets the smallest balance first, paying it off quickly for a psychological win that can sustain motivation. Research shows the snowball method leads more people to successfully eliminate debt, even though it costs slightly more in interest. Choosing the right strategy depends on whether you are more motivated by math savings or behavioral momentum.
Why does paying only the minimum payment keep me in debt so long?
Minimum payments on credit cards are often set at just 1–2% of the balance or a small fixed floor, barely covering the monthly interest charge. As a result, the principal shrinks extremely slowly — a $5,000 balance at 20% APR with a fixed $100 minimum can take over 8 years to clear and cost more than $3,000 in interest. Card issuers design minimums this way because prolonged balances maximize their revenue. Paying even modestly above the minimum dramatically shortens the timeline and slashes interest costs.