Debt Snowball Calculator: Free Avalanche Comparison

Compare debt snowball and avalanche using the same fixed monthly budget. Snowball targets the smallest starting balance first; avalanche targets the highest annual rate first. Paid-off minimum payments stay in the budget and roll into the next debt.

How the debt snowball works

Pay the entered minimum on each active debt, then direct remaining budget to the smallest starting balance. Once it is cleared, send the available payment to the next debt in the same month. This tool fixes the priority order from the starting balances rather than reordering balances each month.

Avalanche instead prioritizes the highest annual rate. Ties use the smaller starting balance, then entry order. Snowball ties also use entry order. Both plans use an identical budget: original minimum payments plus Extra monthly payment, even as debts are repaid.

Worked example with no interest

For Debt 1 enter Balance 1000, Annual interest rate (%) 0 and Minimum monthly payment 100. For Debt 2 enter Balance 2000, Annual interest rate (%) 0 and Minimum monthly payment 100. Enter Extra monthly payment 100 and select Compare repayment plans.

The starting debt is 3000.00 and fixed monthly budget is 300.00. Both strategies finish in 10 months with zero interest. Debt 1 is cleared in month 5; its payment capacity then goes to Debt 2. This illustrates rolling payments without claiming that both strategies always have identical results.

How interest and payments are modeled

At the start of each modeled month, interest on each remaining balance equals balance x (annual rate / 100) / 12, rounded half up to the nearest cent. The calculator adds interest, pays up to the fixed minimum on each active debt, and applies all remaining budget in strategy order.

A payment is capped at the balance due, and unused payment capacity moves to another debt in that month. The final month's actual payment may be smaller than the budget. Total interest counts accrued interest; total paid counts actual payments. Remaining balances include any interest not yet paid.

When a plan does not finish

Each comparison runs for at most 600 months. If debts remain, the result says they are not repaid within that horizon and shows the remaining balance. It does not claim a payoff date or label an incomplete interest total as a lifetime cost.

A minimum smaller than monthly interest can allow a balance to grow while another debt is targeted. Extra payments or rolled payments may eventually reduce it, but a small budget can still fail to clear all debts within the horizon. Review the actual account requirements; entered minimums are assumptions, not a determination of what your lender requires.

Compare methods fairly

Avalanche often reduces interest by prioritizing higher-rate debt; snowball emphasizes clearing smaller starting balances. The result depends on the actual rates, amounts and payment assumptions. The calculator compares the plans without assuming either is always better or predicting which one you will follow.

Promotional rate expirations, variable rates, fees, late payments, changing minimums and new purchases are excluded. Student loans, secured debt and special repayment arrangements can have rules that this model does not cover. For one automobile loan with extra payments, use the Car Loan Payoff Calculator.

For a step-by-step walkthrough, read How to Calculate Debt Snowball Payments and Compare Avalanche.

Inputs and privacy

Enter 1 to 20 debts. Each balance and minimum payment must be greater than zero and at most 10000000; Extra monthly payment may be zero up to 10000000. Money inputs support two decimals and annual rates 0 to 100 percent support four decimals. Amounts use exact integer cents. A currency with two decimal places is assumed.

Calculations run locally in your browser. This calculator does not save or transmit your debt entries. The hosting website may use separate analytics or advertising services.