Debt Payoff Calculator – Snowball vs Avalanche
Compare the debt snowball and debt avalanche strategies side by side. Enter each debt's balance, APR and minimum payment plus your total monthly budget to see which method gets you debt-free faster and cheaper.
Compare Debt Payoff Strategies
Debt Snowball Formula
Where:
- \(b_j\) — current balance of debt \(j\)
- \(r_j\) — its annual percentage rate (APR), written as a decimal
- \(i_j\) — interest added to debt \(j\) during one month
- \(m_j\) — required minimum monthly payment on debt \(j\)
- \(B\) — total monthly budget available for all debt payments
- \(R\) — extra money left each month after all minimums are covered
Each month the calculator adds interest to every open balance, pays every minimum, and directs the remainder \(R\) to one priority debt: the smallest balance (snowball) or the highest APR (avalanche). When the priority debt reaches zero, its freed-up minimum plus \(R\) roll onto the next target, so the payment "snowball" grows every time a debt disappears.
Debt Snowball – Calculation Example
Example: three debts — a credit card with a $3,000 balance at 24.9% APR and a $90 minimum, a store card with $800 at 18.9% and a $40 minimum, and a personal loan of $6,000 at 11.5% with a $200 minimum — paid down with a total monthly budget of $500.
The minimums total \(90 + 40 + 200 = \$330\), so \(R = 500 - 330 = \$170\) goes to the priority debt each month. In month 1 the snowball attacks the store card (smallest balance):
\[ 800 \times \tfrac{0.189}{12} + 800 = 812.60, \quad 812.60 - 40 - 170 = \$602.60 \]
Result: with these numbers the snowball clears all three debts in about 23 months, paying roughly $1,508 in interest. The avalanche, which attacks the 24.9% credit card first, also finishes in about 23 months but pays roughly $1,466 in interest — saving about $42.
How to use the calculator
- Set Number of debts (from 1 to 10). The form displays exactly that many debt sections.
- For each debt, type a Name (optional, e.g. "Credit card"), its current Balance, its APR, and the Minimum payment you must make each month.
- Enter your Total monthly budget for debt — every dollar you can put toward debt repayment in a month. It must be at least as large as the combined minimum payments.
- Read the verdict line, which tells you which strategy saves more and by how much.
- Compare the snowball and avalanche side by side: months to debt-free, debt-free date, total interest paid, and the payoff order of each debt.
- Open the Snowball monthly schedule or Avalanche monthly schedule to see every balance, payment and interest charge month by month.
Debt snowball vs. debt avalanche
Both strategies use the same core idea: pay all minimums, then throw every remaining dollar at one debt at a time. They differ only in how they choose the target. The snowball attacks the smallest balance first, so you wipe out individual debts quickly — the store card disappears early, and that visible progress is a powerful motivator. Each time a debt is cleared, its minimum payment is added to the attack on the next-smallest balance, which is where the "snowball" name comes from.
The avalanche attacks the highest interest rate first. Mathematically it is the cheapest option: for a fixed monthly budget, no ordering generates less total interest than always killing the most expensive debt. In the default example above it saves about $42 — in other situations, especially with large high-APR balances, the gap can run into thousands of dollars.
So why does anyone pick the snowball? Because the cheapest plan on paper is worthless if you abandon it. Research on debt repayment behavior suggests many people stick with the snowball longer because closing an account early feels like real progress, and consistency matters more than a few dollars of interest. This calculator shows you the actual trade-off for your debts, so the decision is a number rather than a guess.
Interpreting the result is simple: if the avalanche saves only a trivial amount, pick whichever strategy you find easier to follow — favoring the snowball for its early wins. If the avalanche saves hundreds or more, seriously consider it, especially if your highest-rate debt is also a large one. To see how a single high-APR balance compounds, try our credit card interest calculator.
Quick comparison
| Snowball | Avalanche | |
|---|---|---|
| Priority | Smallest balance first | Highest APR first |
| Interest paid | Slightly more | Always the minimum possible |
| Time to debt-free | Same or slightly longer | Same or shorter |
| Psychological edge | Fast early wins | Satisfying to watch expensive debt shrink |
| Best for | People who need momentum | People motivated by total savings |
Assumptions, limitations and tips
- The calculator assumes you stop making new charges and keep the monthly budget constant until every balance is zero. If your budget varies, run the calculator again with a realistic average.
- Interest is accrued monthly as balance × APR ÷ 12, which matches how most credit cards and loans compute it. Balances with daily compounding or grace periods may differ slightly.
- Minimum payments are treated as fixed amounts, not as a percentage of the shrinking balance. If your minimums decline as balances fall, the results will be somewhat different.
- Fees, promotional 0% periods that later expire, and statements made mid-cycle are not modeled. Enter an APR that reflects what the rate will actually be over the payoff period.
- If your budget barely covers the minimums, most of each payment goes to interest and progress will be painfully slow. Before committing, check your debt-to-income ratio to see how stretched you really are.
- A debt consolidation loan can turn several payments into one at a lower blended rate — worth comparing against both strategies when you have good credit.
- Once unsecured debts are gone, the same snowball logic works on larger loans; our mortgage payoff calculator with extra payments shows the effect of rolling your freed-up budget into a home loan.
- If one debt has an extremely high APR (for example a payday loan), attacking it first is wise under either method — put it at the top of the list regardless of strategy.
Frequently Asked Questions
Can the snowball ever be cheaper than the avalanche?
Only in rare cases tied to the calculator's simplifications. Mathematically, the avalanche always minimizes total interest for a fixed monthly budget. But if a debt is cleared in the same month under both strategies, or interest is rounded to cents on tiny balances, the two totals can come out a few cents apart, occasionally even equal. If you see the snowball winning by a noticeable amount, double-check that you entered the same balances, APRs and minimums for both runs — they are always simulated from identical inputs.
How do I calculate the snowball or avalanche plan by hand?
List every debt with its balance, APR and minimum payment. Pay all minimums, then put your leftover money toward one target: the smallest balance (snowball) or the highest APR (avalanche). Each month the balance grows by interest — balance × APR ÷ 12 — then shrinks by what you paid. When the target hits zero, roll its freed-up minimum into the next target and repeat until every debt is gone.
What monthly budget should I enter?
Enter every dollar you can realistically put toward debt each month: minimum payments plus any extra you can commit, not just the minimums. If your income varies, use a conservative monthly average rather than your best month. A budget barely above the combined minimums keeps you in debt far longer; even an extra $50–$100 a month can cut years and hundreds of dollars in interest off the payoff.
What should I do with a debt that has 0% promotional APR?
Include it with a 0% APR, but understand that the avalanche will rank it last while the promotional rate lasts. The risk is that the promo period expires and the rate jumps — sometimes to 25% or more. If the 0% will end before you can pay it off, consider entering the rate you expect after the promo expires instead, or plan to clear it just before the deadline. The calculator does not model expiring promotional rates, so reflects the jump manually.
Why does the calculator say my debts will never be paid off?
That happens when interest accrues faster than your payments reduce the balances — for example, a $10,000 card at 29% APR gains about $242 in interest each month, so paying $200 makes the balance grow. The calculator stops after 100 years and reports failure. The fix is to raise the total monthly budget above the combined monthly interest, ideally well above it. If that is impossible, contact your lenders about hardship programs or seek help from a nonprofit credit counseling agency.
Do snowball and avalanche work for mortgages, auto loans or student loans?
Yes, any debt with a fixed rate and monthly payment fits. Just enter the remaining balance, APR and required payment. One caution: extra principal payments on some mortgages, auto loans or private student loans may trigger prepayment penalties, and some loans apply extra money to future payments rather than principal — check with your lender first. Also make sure you keep an emergency fund so a surprise expense does not land back on a credit card.
Which debts should I include — and should my emergency fund come first?
Include all debts you plan to attack: credit cards, store cards, personal loans, medical bills, student loans. Many advisers suggest keeping a small starter emergency fund (often $500–$1,000) before beginning an aggressive payoff, so a small emergency does not push you deeper into debt. Once the payoff is complete, redirect the entire monthly budget toward building a full 3–6 month emergency fund — you are already used to living without that money.