Instrument 08 · Borrow
Debt Snowball vs Avalanche Calculator Two Roads Out. One Is Cheaper.
The avalanche method pays debts from the highest interest rate to the lowest and always costs the least interest. The snowball method pays from the smallest balance to the largest and clears whole debts sooner. Both pay every minimum and roll each freed payment into the next debt. Enter your debts to see the difference in months and money.
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Every unit above the minimums goes to one debt at a time. When that debt clears, its minimum joins the attack on the next — that rolling payment is the engine, and both methods use it. Only the order differs.
Avalanche Cheapest
Snowball Fastest wins
Add a debt to compare the two methods.
Attack order — avalanche
At 24.9% your most expensive balance doubles in 2.8 years
Reading Your Result
What The Number Is Telling You.
- Methods within 5% of each other
- Take the one whose first win comes sooner.
- Avalanche saves more than 5%
- Take the cheaper road unless you know you need early wins.
- A minimum below its interest
- That debt grows every month. Fix it before choosing a method.
The Model
The Formula, In Full.
The arithmetic this instrument runs, with a worked example. Its test cases are published on the methodology page
Monthly interest = balance × APR ÷ 12
Pay every minimum; send all extra to the target debt (highest APR for avalanche, smallest balance for snowball)
When a debt clears, its minimum rolls into the next targetWorked example. The page boots on a seed where the avalanche finishes in 30 months with $2,758 of interest and the snowball costs $2,851.
Assumptions and edge cases
- Interest is charged monthly at APR ÷ 12; card issuers usually charge daily, so real figures differ slightly.
- Rates and minimums stay fixed.
- No new borrowing during the plan.
| Edge case | Behaviour |
|---|---|
| Minimum below interest | Flagged — the balance grows. |
| Identical results | Both shown; the copy says the choice is free. |
| 0% APR debt | Avalanche orders it last. |
| Runaway horizon | Capped with a message (v4 invariant). |
Questions
Debt Payoff, Answered Plainly.
What is the debt avalanche method?
The avalanche method pays the minimum on every debt and sends every spare unit to the debt with the highest interest rate, regardless of its balance. When that debt clears, its payment rolls onto the next-highest rate. It is mathematically optimal: for a given monthly budget it always produces the lowest total interest and never finishes later than the snowball.
What is the debt snowball method?
The snowball method pays the minimum on every debt and sends every spare unit to the smallest balance, regardless of interest rate. When that debt clears, its payment rolls onto the next-smallest. It costs more interest than the avalanche, but it removes whole debts from the list sooner, which is what makes month three feel different from month one.
Which is better, avalanche or snowball?
Avalanche is always cheaper on paper. Whether it is better depends on whether you finish. Run both above: if the avalanche saves a large amount, take the cheaper road. If the two are within a small margin — common when balances are similar — take the one whose first win arrives sooner, because a plan abandoned in month four costs more than either.
Should I pay off debt or save first?
A common sequence is a small starter emergency fund first, then aggressive debt payoff, then a full fund. With no buffer at all, the next unexpected expense goes back onto the card you are paying down, which undoes the progress and the motivation together. Once a small buffer exists, every spare unit is worth more against a high interest rate than in a low-yield account.
Does making extra payments actually help?
Substantially, and more than linearly. Interest accrues on the balance, so every extra unit paid early reduces every future interest charge on that balance. Move the extra-payment dial above and watch both the months and the interest fall. The effect is largest on the highest-rate debt, which is why the avalanche sends extra money there first.
How is credit card interest calculated?
Most card issuers divide the APR by 365 to get a daily rate, apply it to your average daily balance, and add the result at the end of each billing cycle. This calculator uses the APR divided by 12 each month, which lands very close for comparison purposes. At a 24 per cent APR, an unpaid balance roughly doubles in three years — the Rule of 72 calculator shows the exact figure.
How long does it take to pay off a credit card with minimum payments?
Often many years, because the minimum is usually a small percentage of the balance plus interest, so it shrinks as the balance does. The exact rule differs by issuer and is printed on your statement; in the United States, statements must also show how long paying only the minimum would take. Enter the card above with no extra payment to see your own figure, then add a fixed amount and compare.