Loan Debt Avalanche Calculator
The avalanche kills the most expensive debt first — the mathematically cheapest way out. Enter up to six debts and one monthly budget, and this calculator runs the avalanche and the snowball on the same numbers: months to debt-free and total interest, side by side.
The race — both plans on your numbers
| Plan | Debt-free in | Total interest | Payoff order |
|---|---|---|---|
| Run the race to see both plans. | |||
How it works
Each month, every debt accrues interest on its balance and receives its minimum payment. The rest of your fixed budget attacks a single target debt — the highest APR in the avalanche, the smallest balance in the snowball. When a debt dies, its minimum rolls into the attack money. The avalanche never costs more interest than any other order; its only weakness is that the first victory can take longer to arrive.
Formula & worked example
Formula: Each month every debt accrues interest (balance × APR ÷ 12) and receives its minimum; the rest of the fixed budget attacks one target — the highest APR (avalanche) or the smallest balance (snowball). A cleared debt’s minimum rolls into the attack money, so the attack grows as the list shrinks.
Worked example: Debts of $500 at 18% (minimum $25), $3,000 at 22% (minimum $60) and $8,000 at 8% (minimum $150), paid with a $400 monthly budget: both plans finish in 34 months. The avalanche pays $1,726.54 of interest, the snowball $1,747.70 — the avalanche saves $21.16 here, and its first kill is the 22% card instead of the $500 store card.
Frequently asked questions
Avalanche or snowball — which is actually better?
On math, the avalanche: it never costs more interest, and often costs less. On the example debts here ($500 at 18%, $3,000 at 22%, $8,000 at 8%, $400 a month), both plans finish in 34 months — the avalanche pays $1,726.54 of interest against the snowball’s $1,747.70, a $21.16 edge. The snowball’s counter-argument is behavioral: clearing the $500 debt early keeps people going.
Why does the avalanche attack the highest rate first?
Because interest is the rent you pay on each dollar of debt, and the highest-rate dollars charge the most rent. Removing them first shrinks every future month’s interest bill by the largest possible amount.
What budget should I enter?
Everything you can genuinely put toward these debts each month, minimums included. If the budget is below the sum of the minimums, no plan can work — the calculator will tell you the minimums alone need more.
The interest difference looks small. Does order even matter?
With small balances and short timelines, honestly, not much — $21.16 on the example stack. The gap widens with bigger balances, wider rate spreads and longer timelines. Run your real numbers: if the gap is small, pick whichever order you will actually stick to.
❄️ Small wins first instead?
The Debt Snowball Calculator leads with the smallest-balance plan and races the same two methods from the other side.