Debt Avalanche vs Snowball Calculator: Compare Payoff Methods

The two named approaches to multi-debt payoff are the avalanche (extra dollars to the highest-APR balance first) and the snowball (extra dollars to the smallest balance first). The CFPB does not endorse either method — both work if the borrower stays the course. The right one for you depends on the math of your specific debts and on what keeps you paying consistently month after month.

This calculator runs both simulations on your real balances and APRs at the same monthly payoff budget, then shows months to debt-free, total interest paid, balance curves over time, and a verdict that tells you exactly how much each method costs or saves versus the other. No login, no tracking, no localStorage — the math runs entirely in your browser.

The avalanche method directs all extra payment dollars to the debt with the highest APR until that balance reaches zero, then rolls the entire freed-up payment down to the next highest APR. Minimum-interest discipline kicks in immediately because the most expensive dollar of debt is the one being attacked first.

For most borrowers with mixed credit-card and installment debt, avalanche minimizes total interest paid — sometimes by hundreds, sometimes by thousands of dollars compared with snowball, depending on the spread between the highest and lowest APR. The trade-off: if the highest-APR debt also happens to be the biggest balance, it can take many months before the borrower sees any account fully retired. Visible progress is slower.

The snowball method directs extra dollars to the debt with the smallest balance first, regardless of APR. The first account is typically retired within a few months, which creates a visible win, builds momentum, and freed-up minimum payments roll into the next account.

The research on snowball vs. avalanche is mixed. A frequently cited Harvard Business Review study found that consumers were more likely to complete debt payoff when they focused on closing smaller balances first. If past attempts at debt payoff have stalled out, snowball can be the right answer even when avalanche would technically cost less in interest. The calculator quantifies the trade-off so you can decide.

Each month the calculator: (1) adds monthly interest = balance × (APR ÷ 12) to every account that still has a balance, (2) sorts active accounts by avalanche or snowball priority, (3) applies the full monthly payoff budget starting from the top of the priority list and cascading down once a balance hits zero, (4) records the new total balance for the chart, (5) repeats until every balance is zero or 600 months pass.

If the monthly budget cannot cover total monthly interest across all active debts, the calculator triggers a warning — this is the “negative amortization” case where the balance grows even with payments applied. The fix is almost always a higher monthly budget; if that isn’t possible, the next step is usually a hardship plan from the lender or a CFPB-listed nonprofit credit counselor.

The default inputs in the calculator load three illustrative debts: a $4,200 credit card at 24.99% APR, an $8,000 personal loan at 12.5%, and a $1,200 store card at 28.99%. At a $600 monthly payoff budget, avalanche attacks the 28.99% store card first, then the 24.99% credit card, then the personal loan. Snowball attacks the $1,200 store card first (smallest balance), then the $4,200 credit card, then the personal loan.

In this specific scenario both methods reach the same first target because the smallest-balance debt also happens to carry the highest APR. The order diverges on debts two and three: avalanche pays the 24.99% credit card next, snowball pays the $4,200 credit card next. Change one input — for example, raise the personal-loan APR above the credit-card APR — and the verdict changes immediately. Try it.

If your highest-APR debt is also the smallest balance, avalanche and snowball converge. If your highest-APR debt is much larger than the others, avalanche saves materially more. If all your APRs are similar (e.g., a portfolio of three credit cards all between 22% and 26%), the two methods produce nearly identical interest costs and the “right” one is whichever you will actually stick with.

For most borrowers we recommend running both simulations once a year and re-checking after a big change — a balance transfer, a personal loan to consolidate, a missed payment that bumped an APR to a penalty rate. The right method is rarely a permanent decision; it’s a recurring one.