Number 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.
When to use this
- You have several debts at very different rates and want the cheapest order, proven on your own numbers.
- You are disciplined enough not to need an early win, so the snowball's motivation premium buys you nothing.
- One debt carries a rate in the high twenties and you suspect it should die first regardless of its size.
- You want the avalanche and the snowball raced on identical numbers before committing to either.
How to use it, step by step
- Add one row per debt (up to six): a name, the balance, the APR and its current minimum payment.
- Enter one total monthly budget that covers every minimum with something left over to attack with.
- Run the race and read the avalanche row first: months, total interest and the payoff order.
- Note when the highest-rate debt dies — that is when the monthly interest bill drops fastest.
- Compare against the snowball row: if the saving is small on your numbers, the order matters less than the budget.
What the inputs mean
| Input | What it is | Typical values |
|---|---|---|
| Balance (per debt) | What each debt currently owes, one row per debt | From a $200 store card to a five-figure loan |
| APR (per debt) | Each debt's own rate — this is the avalanche's sorting key | Cards 18–30%; loans usually far lower — the spread drives the result |
| Minimum payment (per debt) | The dollar minimum you must pay monthly on each | Use the current statement figure |
| Total monthly budget | One fixed pot covering all minimums plus the attack money | Must at least equal the sum of the minimums |
Another worked example
Three debts — a $950 credit union loan at 9.5% (minimum $35), a $2,400 store card at 27.99% (minimum $70) and a $5,600 bank card at 18.5% (minimum $110) — paid from a $525 monthly budget. The avalanche attacks the 27.99% store card first and clears it in month 7, finishing all three debts in 20 months with $1,493.27 of interest. The snowball on the same budget needs 21 months and $1,651.71: the avalanche saves $158.44 and a month, but its first debt takes seven months to die instead of three.
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.
What if two of my debts have the same APR?
Then the order between them costs the same either way — a dollar of principal removed from one saves exactly what it would save on the other. This calculator works through tied rates in the order the debts are listed, and in practice it makes sense to clear the smaller of the two first for the freed minimum, since the interest saving is identical.
Can the avalanche ever finish later than the snowball?
The month count is driven mostly by the budget and the total owed, so the two plans usually tie on time — and the avalanche can occasionally finish sooner, as in the worked example on this page, where killing the expensive balance early leaves more of the budget hitting principal. Order mainly moves the interest total; when it moves the finish date at all, it tends to move it in the avalanche's favour.