Debt snowball vs. avalanche: which pays off debt faster?

With the same debts and the same monthly total, the avalanche (highest APR first) normally pays the least interest and finishes at the same time or a little sooner. The snowball (smallest balance first) pays off its first debts sooner. In the example below, with four debts totaling $21,900 and $1,000 a month to spend on them, the avalanche saves $594.00 and one month, while the snowball clears its first debt in month 6 instead of month 9. Both beat paying minimums by far more than they beat each other.

How do the debt snowball and debt avalanche work?

The snowball targets debts in order of balance, smallest first, and the avalanche in order of APR, highest first. Otherwise the two follow the same routine:

1. List every debt with its balance, APR and minimum payment.
2. Pick one monthly total for debt that covers all the minimums, and keep it fixed.
3. Pay every minimum and send the rest of the total to one target debt.
4. When the target is paid off, keep its payment in the plan and move to the next target. In the month a debt is cleared, the leftover goes straight to the next one.

The CFPB frames the pair as a choice between saving the most money and seeing progress sooner. “Minimums only” is the baseline: each debt gets its minimum, and a paid-off debt’s payment leaves the budget.

How much does the avalanche save? A worked example

On the four debts below, the avalanche saves $594.00 of interest and finishes one month sooner than the snowball. Example assumptions, not current rates or anyone’s real accounts: four debts, minimums held at today’s amounts, and $1,000 a month, which is $290 more than the $710 of minimums. Each month’s interest is balance × APR ÷ 12, rounded to the cent. There are no new charges or fees.

Month 1 costs the same either way. Interest is $17.40 + $76.18 + $115.95 + $229.60 = $439.13, so only $560.87 of the first $1,000 reduces balances. The snowball sends the $290 extra to the personal loan and the avalanche sends it to the store card. From there the plans split:

After 12 months the snowball has paid off two debts and still owes $14,523.24. The avalanche has paid off one and owes $14,325.73. The avalanche never targets the personal loan at all: its own $95 payments clear it in month 23, before the avalanche gets to it.

Where does the interest difference come from?

It comes from the rate gap on the extra dollars, for as long as they sit on the cheaper debt. After month 1 the snowball owes $290 more than the avalanche on the 29.49% store card and $290 less on the 10.99% loan. Month 2’s interest is $431.69 under the snowball and $427.23 under the avalanche: a $4.46 gap, which is $290 × 18.50% ÷ 12 give or take a cent of rounding.

The gap compounds as more money lands on cheaper debts. Left until last at 26.24%, the Mastercard costs the snowball $1,344.09 more and the store card $274.00 more; savings of $869.02 on the Visa and $155.07 on the personal loan bring the net to $594.00.

The debt-free date barely moves because both plans pay the full $1,000 every month but the last. The payoff month is everything you pay divided by the monthly total, rounded up: $29,528.96 gives month 30 for the snowball and $28,934.96 gives month 29 for the avalanche. The time saved is roughly the interest saved divided by the monthly total: $594.00 ÷ $1,000 is 0.6 of a month, which here happens to tip the finish from month 30 to month 29.

What does rolling over a payment mean, and how much does it matter?

Rolling over means that when a debt is paid off, its payment moves to the next debt instead of back into your spending, so the monthly total never drops. It is a separate effect from adding extra money, and the example shows both:

Rollover alone finishes 8 months sooner and saves $1,173.15 to $1,235.42 of interest. The $290 extra saves another 20 or 21 months and $5,510.88 to $6,042.61. The size of the monthly total matters more than the order:

Raising the total from $1,000 to $1,200 saves the avalanche $1,640.21, nearly three times the gap between the methods. The snowball’s head start is widest when the extra is small: at $800 ($90 above the minimums), the avalanche’s first payoff doesn’t come until month 21, ten months after the snowball’s.

When does a minimum payment never pay off the balance?

When it is no larger than the month’s interest, balance × APR ÷ 12. On the example Mastercard that is $10,500 × 26.24% ÷ 12 = $229.60. Pay exactly that and the balance stays at $10,500.00; pay less and it grows. For a fixed payment $P$ on a balance $B$ at a monthly rate $r$ (APR ÷ 12, as a decimal), the number of payments is:

$$n = \frac{-\ln\left(1 - \dfrac{rB}{P}\right)}{\ln(1 + r)}$$

At $330, $rB/P = 229.60 / 330 = 0.6958$ and $n = 55.01$: 55 payments of $330 and a 56th of $3.47. When $P \le rB$, the logarithm has no value, which is the never-repays case. Just above that line, a few dollars change the payoff time by years:

A minimum set as a share of the balance can land here too. At 26.24%, a month’s interest is 2.19% of the balance, so a minimum of 2% of the balance (the example formula in Regulation Z’s Appendix M1) never covers it, and the Mastercard would grow every month.

Card statements must flag this case. If the minimum payment wouldn’t reduce the balance, Regulation Z §1026.7(b)(12)(ii) replaces the usual repayment estimate with a warning that minimum payments alone will never pay it off because they are less than the interest charged each month. The statement still shows the payment that would clear the balance in 36 months.

Inside a multi-debt plan, such a debt grows while it waits its turn. With a $220 minimum instead of $330 and the same $1,000 total, the snowball would let the Mastercard climb to $10,695.13 by month 17, the month before the plan reached it.

Why does a “1% plus interest” minimum take decades?

Because the payment shrinks with the balance. Card agreements set the minimum by a formula (Regulation Z’s Appendix M1 illustrates one as 2% of the balance or $20, whichever is greater). Take, for example, 1% of the balance plus that month’s interest, with a $25 floor. The interest part only covers the interest, so just 1% of the previous balance is repaid each month, and after $k$ months the balance is:

$$B_k = B_0 \times 0.99^{k}$$

This holds until the floor takes over. Halving the balance takes $\ln 2 \div ({-\ln 0.99}) \approx 69$ months.

On the Mastercard, the first minimum is $105.00 + $229.60 = $334.60, a little more than the fixed $330. After that it shrinks with the balance:

The card is finally paid off after $21,799.53 of interest. Holding the payment at $330 takes 56 months and $7,653.47. That is why a payoff plan freezes each minimum at today’s amount rather than following the card’s formula down.

Your statement already runs this calculation. The minimum payment warning, required by the Truth in Lending Act as rewritten by the Credit CARD Act of 2009 (15 U.S.C. 1637(b)(11)) and by Regulation Z §1026.7(b)(12), shows how long minimum payments alone would take, what they would cost in total, and the payment that clears the balance in 36 months. The estimate uses your card’s own minimum formula and APRs (Appendix M1) and assumes no new purchases. Under the 1%-plus-interest example, the box would read about 26 years and $32,300 in all, against about $424 a month, or $15,278 in all, to finish in 36 months.

Snowball or avalanche: which one should you use?

The arithmetic favors the avalanche. What decides the real result is keeping up the payments until the last debt is gone, and only you can judge which order helps you do that. Researchers at Northwestern’s Kellogg School (Gal and McShane, 2012) examined records of about 6,000 people in a debt settlement program and found that clearing whole accounts, whatever their dollar size, predicted who went on to eliminate their debt. That is an association among settlement clients, not a trial of the two methods, and the authors suggested people be told both the interest-minimizing order and the possible psychological benefit, then choose.

Points that narrow the choice:

• The snowball’s cost scales with the rate gap. Here the rates run from 10.99% to 29.49%. With rates close together the difference shrinks toward zero, and when the smallest debt also has the highest rate, the two orders start the same way.
• A quick first win costs less than a full snowball. Paying off the personal loan first and then switching to the avalanche takes 30 months and $7,408.28 of interest. That is $373.32 more than the pure avalanche and $220.68 less than the snowball.
• Deadlines come before either order. A deferred-interest balance that isn’t paid in full by the end of its promotion is charged interest back to the purchase date. Clearing it on time can matter more than its rank.
• One card with several APRs already follows the avalanche. Under Regulation Z §1026.53, anything paid above the minimum goes first to the highest-APR balance on that card, except in the last two billing cycles of a deferred-interest promotion.

What these numbers leave out

• Real card interest. Some issuers charge a daily periodic rate (APR ÷ 360 or 365) that compounds daily, so a statement’s interest differs slightly from the APR ÷ 12 used here.
• New charges, fees and rate changes. New spending on a card in the plan adds to what you are paying down, and an expiring promotional rate can change the avalanche order.
• A total below the minimums. No order helps if the money doesn’t cover every minimum. The CFPB suggests calling the card company about a lower payment and considering nonprofit credit counseling, and warns against debt settlement companies that charge fees before settling anything.
• Consolidation. A consolidation loan or balance transfer changes the rates themselves, but promotional rates end, transfer fees usually apply, and it doesn’t help if spending keeps outrunning income.

Try it

• Debt snowball vs. avalanche calculator: enter four debts (name, balance, APR, minimum payment): Personal loan, 1,900, 10.99, 95; Store card, 3,100, 29.49, 105; Visa, 6,400, 21.74, 180; Mastercard, 10,500, 26.24, 330. With the budget entered as the total for all debts, set the monthly budget to 1,000 ($290 above minimums). The snowball finishes in 30 months with $7,628.96 of interest, the avalanche in 29 months with $7,034.96, and minimums only in 58 months with $14,312.99. Change the monthly budget to 710 for the rollover-only rows, or to 800, 1,200 or 1,500 for the budget table.
• Credit card payoff calculator: enter a card balance of 10,500 and an APR of 26.24. On the Minimum plan, choose the minimum formula Interest + % of balance, with 1% of the balance and a lowest minimum payment of 25: 312 months and $21,799.53 of interest. Keep those minimum settings: the other plans use them for the “Minimum payments only” line in their results. On the Fixed payment plan, a monthly payment of 330 gives 56 months and $7,653.47 of interest, and 229.60 never pays it off. Paying it off in 36 months takes $424.40 a month: the result shows it under any plan, and the Deadline plan with 36 months gives the same.
• Budget calculator: find how much above your minimums you can put toward debt each month. That monthly total moves the result more than the order does.