Debt Payoff Calculator
See how much faster you’ll be debt-free — and how much interest you’ll save — by adding extra to your payment.
Understanding the Debt Payoff Calculator
This calculator compares two payoff paths side by side: your regular planned monthly payment, and that same payment with an extra amount added on top, applied entirely to reducing principal faster. It’s built for any single balance with a fixed rate — a personal loan, a card, or a consolidated debt.
Extra payments have an outsized effect because they shrink the balance interest is calculated on every month going forward, not just once. Even a modest, consistent extra amount can meaningfully cut both the payoff timeline and the total interest paid, especially on higher-rate debt.
If you’re juggling several separate debts at once, apply this calculator to each one, or focus the extra payment on the highest-rate balance first (often called the “avalanche” method) to minimize total interest across all of them.
See it in practice
Example 1 — Regular payment only
Example 2 — Same debt, plus $100/month extra
Common questions
Check with your lender — most loans let you specify that extra amounts apply to principal, which is what produces the interest savings modeled here. Some servicers default extra payments to ‘next month’s payment’ instead, which doesn’t have the same effect.
Avalanche directs extra payments to the highest-rate debt first, minimizing total interest paid. Snowball directs extra payments to the smallest balance first, which can build momentum and motivation even though it usually costs slightly more in interest.
Many planners suggest a small emergency cushion before aggressively prepaying debt, so an unexpected expense doesn’t force new borrowing. See the emergency fund calculator for a target amount.
Run it once per debt. For several balances, apply any extra amount to one at a time (usually the highest rate or smallest balance, per your chosen strategy) rather than splitting it evenly, which is generally less efficient.
Even a modest extra amount, like $50 or $100 a month, can meaningfully shorten a payoff timeline and reduce total interest. The exact impact depends on your balance and interest rate, which is why running your own numbers is worth doing.
The debt snowball method means paying off your smallest balance first while making minimum payments on everything else, then rolling that payment into the next-smallest balance. It builds momentum through quick wins, though it isn’t always the cheapest mathematical approach.
The debt avalanche method means paying off your highest interest rate balance first, regardless of size, while making minimum payments on the rest. This method minimizes total interest paid, though it can take longer to see a balance fully disappear.
This depends on the interest rate on your debt versus what your savings are earning. For high-interest debt, like credit cards, using savings beyond your emergency fund can make sense. For low-interest debt, keeping savings intact is often the safer choice.
Consolidation can save money if the new loan’s interest rate is genuinely lower than your combined existing rates. It only helps if you avoid running up new balances on the accounts you just paid off, or it can leave you with more total debt.
Debt-to-income ratio, your total monthly debt payments divided by gross monthly income, is a key factor lenders use to evaluate new credit applications. A lower ratio generally means easier approval and better rates on future loans.
For high-interest debt, like credit cards above 15-20%, paying it off first is usually the better choice, since few investments reliably beat that rate. For lower-interest debt, some savers choose to invest instead, though this involves accepting market risk.
Making only minimum payments can mean paying far more in total interest than the original balance, and on some cards, it can take decades to reach zero. Even small additional payments meaningfully shorten this timeline.