Debt Payoff Calculator

ABOUT THIS TOOL

Enter a starting balance, annual interest rate, and monthly payment, and the calculator works out how long payoff will take and the total interest you'll pay over that period. Because interest is charged on the remaining balance each period, even a modest increase to the monthly payment can cut months or years off the timeline and save far more in interest than the extra payment costs upfront. The tool handles one debt at a time — for several balances, most people run each through separately, then decide whether to direct extra payments at the highest interest rate first (avalanche method) or the smallest balance first (snowball method) for psychological momentum.

HOW TO USE

1. Enter the current balance owed on the debt.
2. Enter the annual interest rate (APR).
3. Enter your planned monthly payment.
4. Review the projected payoff date and total interest cost.
5. Increase the monthly payment to see how much time and interest an extra payment saves.
6. Repeat for each separate debt if you're managing more than one balance.

COMMON USE CASES

• Someone with credit card debt deciding how much extra to pay monthly to be debt-free by a target date.
• Comparing avalanche versus snowball strategies across several balances by running each one through separately.
• Deciding whether refinancing a personal loan is worth it by comparing total interest at the old versus new rate.
• Checking whether the card's minimum payment will ever actually clear the balance, or stretch on for decades.
• Planning to redirect a future raise or windfall entirely toward accelerated payoff.

TIPS & COMMON MISTAKES

• Paying only the minimum on a high-interest card can stretch payoff out for years and multiply the total interest paid.
• Extra payments usually apply directly to principal, so even small additions compound into real time savings.
• The avalanche method (highest rate first) minimizes total interest paid when juggling multiple debts.
• Check for prepayment penalties before assuming extra payments are always free to make on every loan type.

MORE QUESTIONS

Avalanche versus snowball — which one actually saves more money?

The avalanche method, which targets the highest interest rate balance first, mathematically minimizes total interest paid across multiple debts. The snowball method, targeting the smallest balance first, often saves less money but can build motivation from quick wins, which matters if sticking with the plan is the bigger challenge.

Why does an extra $50 a month save more than $50 in total interest?

Because that extra amount reduces the principal earlier, and future interest is calculated on a smaller remaining balance. The earlier a payment lands in the payoff timeline, the more compounding interest it prevents down the line.

Does this calculator handle variable interest rates?

It assumes a fixed rate for the calculation. If your debt has a variable rate, rerun the numbers periodically using the current rate to keep the projection accurate as rates change.

What happens if my payment doesn't cover the monthly interest charge?

The balance grows instead of shrinking, a situation called negative amortization. The calculator will show an unrealistic or infinite payoff timeline in that case, which is a sign the payment needs to increase.

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