Debt Avalanche Calculator: Pay the Least Interest
The debt avalanche is the payoff order that costs the least interest: pay minimums on everything and throw every extra dollar at the debt with the highest APR. This debt avalanche calculator shows your payoff date and total interest, and what the same budget would do with the snowball method instead.
Enter your balances, APRs and minimum payments, add your monthly extra, and keep the Avalanche button selected. The sample rows are just placeholders.
Avalanche in 60 seconds
Every debt charges interest on its balance each month. A dollar of extra payment removes a dollar of balance, so it stops interest at whatever rate that debt carries. Put it on a card at 29.99% and it stops more interest than on a car loan at 7.5%. The avalanche simply keeps doing that until everything is gone:
- List your debts from the highest APR to the lowest.
- Pay the minimum on all of them every month.
- Put all extra money on the top debt.
- When it's paid off, add its minimum to the extra and move to the next APR down.
Balance size doesn't matter for the order. A $6,000 card at 29.99% comes before a $1,200 card at 19.99%, even though the small one could be gone in a few months.
For a fixed monthly budget, with rates and minimums that stay the same, no other order will realistically cost you less interest. That's the whole appeal. The cost is psychological: if your highest-rate debt is also your biggest, your first paid-off account may be a long way out.
Example with 3 cards
Three credit cards and $250 a month on top of the minimums:
| Card | Balance | APR | Minimum |
|---|---|---|---|
| Card A | $1,200 | 19.99% | $40 |
| Card B | $3,500 | 24.99% | $105 |
| Card C | $6,000 | 29.99% | $180 |
That's $10,700 in debt, $325 in minimums, and a total budget of $575 a month. In the first month alone, the three cards charge $242.83 in interest, and $149.95 of that comes from Card C.
Here's how the two methods play out on the same budget:
| Avalanche | Snowball | |
|---|---|---|
| Payoff order | C, B, A | A, B, C |
| First card paid off | Month 18 | Month 5 |
| Second card paid off | Month 23 | Month 14 |
| Debt-free in | 24 months | 25 months |
| Total interest | $3,185.75 | $3,600.09 |
The avalanche saves $414.34 and finishes a month earlier. For comparison, paying only the minimums on each card and nothing more would take 73 months and cost $10,066.61 in interest. Either method is a huge improvement over that; the avalanche is just the cheaper of the two.
How big the gap is depends on your extra payment. On the same three cards:
| Extra per month | Avalanche | Snowball | Avalanche saves |
|---|---|---|---|
| $100 | 38 months, $5,200.35 | 39 months, $5,735.70 | $535.35 |
| $250 | 24 months, $3,185.75 | 25 months, $3,600.09 | $414.34 |
| $500 | 16 months, $2,001.68 | 16 months, $2,259.49 | $257.81 |
The smaller your extra, the longer the debts stay open, and the more the order matters. With a big extra payment, everything gets paid off fast and the difference shrinks.
Notice one more thing: if Card A had the 29.99% rate and Card C the 19.99%, both methods would pick the same order, and the results would be identical. Small balances with high rates make the choice easy.
When avalanche loses
The avalanche wins on paper every time. In real life, a few situations tip the scales the other way.
You need a win to keep going
In the example, the avalanche makes you wait 18 months for your first paid-off card. The snowball gets you there in month 5. If you've started and abandoned payoff plans before, a closed account in five months may be worth more than $414. A plan you stick with beats a cheaper plan you quit. We go through this trade-off in detail in which debt to pay off first.
The rates are close
Take two cards: $900 at 23.99% with a $30 minimum, and $7,000 at 24.99% with a $210 minimum, plus $250 extra. The avalanche goes after the big card because its rate is one point higher. Total interest: $1,810.59 over 20 months. The snowball clears the small card first: $1,823.90, also 20 months. The difference is $13.31, and the snowball closes an account in month 4 instead of month 19. When rates are within a few points, the snowball costs almost nothing.
A 0% promo is about to end
A balance transfer or store card at 0% sits at the bottom of the avalanche list. That's correct only while the promo lasts. When it ends, the rate jumps, and some store-card promotions use deferred interest: if the balance isn't fully paid by the end date, interest going back to the purchase date can be added. Check your card agreement to see which kind you have.
Two practical fixes: enter the promo balance at its after-promo APR if it won't be paid off in time, or divide the balance by the months left and make sure at least that much goes to it every month.
You need monthly cash flow now
If your income just dropped, or you're about to apply for a lease or a mortgage, lowering your required monthly payments may matter more than total interest. In that case, paying off the debt with the largest minimum first frees up cash fastest. The full DelDebt planner has this as a separate "cash flow" method.
Calculator
Use the calculator at the top of the page with your real numbers. A few tips so the results match your life:
- Use today's balances and minimums from your latest statements. Credit card minimums usually drop as the balance falls; the calculator keeps each minimum fixed, which is exactly what you should do with your payments.
- Split promo balances: if one card has a 0% portion and a regular portion, enter them as two rows.
- Compare both methods: in Avalanche mode, the line under the results shows what the snowball would cost on the same numbers. If the difference is small, pick the method you'll actually follow. The debt snowball calculator article walks through the snowball month by month.
- Expect small differences from your statements: the calculator charges APR divided by 12 every month, while card issuers accrue interest daily.
When you've settled on an order, save it in the full DelDebt planner. It keeps your debts, marks payments, reminds you of due dates and adds more methods, including blizzard and your own custom order. It's free, and you can use it without an account.
FAQ
Is the avalanche the same as paying the highest interest rate first?
Yes. "Avalanche" is just the popular name for ordering your debts by APR, highest first, and sending all extra money to the top one while paying minimums on the rest.
What if two debts have the same APR?
Put the smaller balance first. You'll pay essentially the same interest and get a paid-off account sooner.
Should my mortgage or student loans be part of the avalanche?
They can be, but with typical rates they'll land at the bottom of the list anyway. Many people focus the avalanche on cards and personal loans and keep the mortgage on its regular schedule. For federal student loans, check repayment options on studentaid.gov before paying extra.
The calculator says minimums don't cover the interest. What now?
That means at least one balance would grow if you paid only minimums. Add an extra amount until a payoff date appears, and consider calling the lender about a lower rate or a hardship program.
How accurate are the results?
Close, not to the penny. Your lender's daily interest, fees and any rate changes will move things by a few dollars. The full planner lets you compare its interest with your statements and adjust.