Debt Payoff Calculator

How the avalanche and snowball methods work

Both methods make the same minimum payments on every debt each month. The difference is where any extra payment goes. The avalanche method directs extra funds to the debt with the highest APR, which mathematically minimises total interest paid. The snowball method directs extra funds to the debt with the smallest remaining balance, which eliminates individual debts faster and provides a psychological boost from clearing accounts sooner.

Once a debt is fully paid off under either method, its freed-up minimum payment rolls into the next target debt, creating a growing payment that accelerates the remaining payoff. This cascading effect is why both methods are sometimes called the debt snowball or debt avalanche — the payment grows as debts disappear.

Core formulas used in this calculator

The calculator uses a month-by-month simulation that applies interest, distributes minimum payments, and then allocates extra funds according to the chosen method. It runs both strategies in parallel so you can compare outcomes.

Worked example: three debts with extra payment

Suppose you have a credit card with a 5,000 balance at 22% APR (100 minimum), a car loan with 10,000 at 6% (200 minimum), and a student loan with 3,000 at 5% (50 minimum), plus 100 extra per month. The avalanche method would direct the extra 100 to the credit card first because it has the highest rate, saving the most interest overall. The snowball method would direct it to the student loan first because it has the smallest balance, clearing that account in roughly 25 months for a quick psychological win.

In this scenario, the avalanche method typically saves several hundred in total interest and finishes a few months sooner. But the snowball method eliminates the first debt earlier, which some people find more motivating. The calculator shows both side by side so you can decide which trade-off suits your situation.

Limitations of this estimate

This calculator assumes fixed APRs, consistent monthly payments, and no new charges added to any balance. Real-world debts may have variable rates, promotional periods, balance transfer fees, penalty APRs, or issuer-specific payment allocation rules that differ from this model. It also does not account for changes in income, unexpected expenses, or tax implications of debt repayment strategies.

Use this tool for planning and method comparison, not as a substitute for personalised financial advice. If you are struggling with debt, consider speaking to a non-profit credit counselling service for guidance tailored to your situation.

Using the blended debt calculator snapshot

Before choosing a payoff method, the calculator summarizes total debt, blended APR, current monthly budget, and first-month interest across all entered balances. That preserves the broad debt calculator workflow: first understand the size and cost of the debt load, then choose a payoff strategy.

The target payment table estimates the monthly payment needed to clear the blended balance over common timelines. It is a planning shortcut for questions like monthly payment to be debt free in two years, how much interest will I pay on debt, and whether the current budget is high enough to reduce principal.

Custom priority and multiple debt payoff planning

Avalanche and snowball are useful defaults, but real payoff plans sometimes need a custom priority. You may need to clear a small account before applying for a mortgage, remove a co-signed balance first, or prioritize a lender with tougher terms. The custom priority mode follows the order shown in the debt list while still rolling freed minimum payments forward as each balance reaches zero.

The extra payment scenarios show how different monthly add-on amounts change payoff time, total interest, and total paid. This keeps multi debt payoff calculator and pay off multiple debts calculator intent on the master page without maintaining a separate thin variant.

Using a one-time lump payment

Many payoff plans are not only about a fixed monthly extra payment. Tax refunds, annual bonuses, asset sales, cash gifts, or short-term side income can create a one-time lump payment that changes which debt should be attacked first. The calculator applies the lump payment in the first month after minimum payments, then continues the monthly snowball, avalanche, or custom priority cascade from the reduced balances.

For most users, a lump payment saves the most interest when it reduces the highest-rate balance early. A snowball user may still choose to clear a small balance first if eliminating one account improves motivation or monthly cash-flow flexibility. The method comparison and extra-payment scenario table let you see whether the lump payment makes the avalanche-versus-snowball difference larger, smaller, or irrelevant for your debt list.

Debt consolidation comparison

The debt consolidation section compares the current payoff plan with one fixed-rate replacement loan. It combines the entered balances, applies the consolidation APR and term, includes any origination fee as an added cost, and then compares monthly payment, total interest, total repayment cost, and payoff timing.

A lower consolidation payment is not automatically better. It can reduce monthly pressure while increasing total cost if the new term is much longer or the fee is high. Use the consolidation comparison to decide whether one new loan improves the payoff plan or simply stretches it.