Debt Payoff Calculator
What is a Debt Payoff Calculator?
Debt grows quickly, and paying only the minimum can stretch a balance for years while interest piles up. A debt payoff calculator shows how long your debts will take at your current payment, and what happens when you add extra money each month.
Use the default inputs to see the leverage: $15,000 of debt at 18% APR with a $450 payment. Interest runs about $225 in the first month, so only half of that payment touches the balance. Payoff still takes 3 years and 11 months, with roughly $6,150 in total interest. Add $100 more per month and the payoff drops to 3 years even, interest falls to about $4,800, and you save roughly $1,350 plus 11 months. Push the total payment to $650 and the debt clears in about 29 months with interest near $3,850. Each additional $100 buys a little less than the one before, but every one of them pays.
Four numbers describe your debt: the total you owe across the debts you are modeling, an average interest rate for them, your current combined monthly payment, and any extra you can add each month. The calculator runs two simulations at the monthly interest rate - one at your current payment, one with the extra included - and compares them side by side: payoff time under each plan, interest saved, and time saved. The gap between the two timelines is the price of doing nothing, quantified in months and dollars, and every result updates instantly as you adjust the payment.
Anyone juggling credit cards, personal loans or medical bills can use this to choose between the avalanche and snowball approaches, and anyone with a windfall can test how much a lump-sum prepayment would shorten the road. The model treats your debts as one pool at one average rate, so it cannot sequence individual balances the way a full avalanche plan would - pair it with a list of each debt's rate to direct the extras. It assumes payments never pause and the APR stays fixed; penalty rates, promotional periods and new charges are outside its view. Test several payment levels before committing to one.
Frequently Asked Questions
Should I use the snowball or avalanche method?
The avalanche method pays off the highest-interest debt first, saving the most money in total interest. The snowball method pays off the smallest balance first, giving quick wins that keep you motivated. Both work - pick the one you will stick with.
How much interest do I pay by making minimum payments?
On a $15,000 balance at 18% APR with a $450 monthly payment, you pay about $6,150 in interest over roughly 4 years. Adding an extra $100 each month cuts the payoff to about 3 years and saves roughly $1,350 in interest.
Can I just add extra money to any debt?
You save the most by directing every extra dollar to the debt with the highest interest rate while paying minimums on the rest. Once one debt is cleared, roll its whole payment into the next, creating a cascade that accelerates as you go.
How much extra should I pay each month?
Whatever your budget reliably allows - even $25 shortens the timeline. A practical approach is to start with half of whatever is left after essentials, then raise it after each debt disappears. This calculator shows the marginal effect of each $25 or $100 you add.
Does paying extra hurt my credit score?
No - paying down revolving balances helps your score through lower credit utilization, one of the largest scoring factors. Closing a paid-off card can nudge utilization upward, so many people keep old accounts open and unused. On-time payments matter more than speed, so never skip a minimum to overpay another debt.
Should I build an emergency fund or pay off debt first?
Most planners suggest a small starter fund of $500 to $1,000 alongside minimum payments, then aggressive debt payoff. Without that buffer, the next car repair goes straight onto the high-rate card you just paid down. Once the debts are gone, redirect the full payment into building a three-to-six-month fund.