Debt Snowball vs Avalanche Calculator

How this is calculated

CORRECTED 4 AUGUST 2026. An earlier version of this calculator could report the avalanche method LOSING money against the snowball, which is impossible - paying the highest rate first cannot cost more interest. The fault was in how the formula handled a debt that finishes earlier than expected. The maths has been rebuilt and checked against a month-by-month simulation across roughly 25,000 scenarios, and every figure here is from the corrected version. THE TWO STRATEGIES DIFFER ONLY IN WHICH DEBT GETS THE EXTRA MONEY. Both pay every minimum every month. Both roll a cleared debt's payment into the next one. The only decision is the order: SNOWBALL targets the smallest balance first, AVALANCHE targets the highest interest rate first. ⚠️ AVALANCHE NEVER COSTS YOU MORE. When the two methods target DIFFERENT debts, avalanche saves strictly more interest. When they target the SAME debt - which happens whenever your smallest balance is also your highest rate - the two plans are identical and the saving is exactly $0. There is no combination of balances, rates and minimums where snowball comes out ahead on interest. The open question is how MUCH less, and whether it is worth what you give up. On these defaults it is $866 over the life of the debts. ⚠️ AND SNOWBALL NEVER WAITS LONGER FOR THE FIRST WIN, which is the thing its advocates are actually arguing about. It either gets you there sooner or ties; it is never the slower of the two. Note the first debt to disappear is not always the one you are aiming at - under avalanche a small cheap debt on its minimum can finish before the expensive one you are attacking, and the tool counts that, because it is a real first win. On these defaults snowball clears a debt in 11.2 months; avalanche makes you wait 31.9 months before anything disappears. That is nearly 21 months of paying without ever crossing something off. The saving is real and so is the wait, so the tool shows both rather than declaring a winner. WHY THE DEFAULTS LOOK LIKE THAT: the strategies only diverge when the SMALL debt is the CHEAP one. If your smallest balance also carries your highest rate, snowball and avalanche pick the same debt and the difference is zero - and the calculator will show a saving of $0, which is a real answer meaning 'this decision does not matter, just start'. THE ARITHMETIC IS A CLOSED FORM IN TWO PHASES, WITH ONE BRANCH THAT MATTERS. Each debt has a month count at which it would clear on whatever it is being paid: n = -log(1 - i x balance / payment) / log(1 + i). Phase one runs until the FIRST debt clears - and that is not always the one you are targeting. Avalanche in particular leaves a small cheap debt sitting on its minimum while you attack the expensive one, and that small debt often finishes first. Whichever clears first, the other's balance at that moment is exact: B(1+i)^n - m((1+i)^n - 1)/i. Phase two sends the whole monthly outlay at what is left. YOUR MONTHLY OUTLAY NEVER CHANGES, in either phase - the minimums plus your extra, split differently. So the total paid is simply that outlay multiplied by the total months, and the total interest is that minus what you originally owed. ⚠️ TWO DEBTS, NOT TEN, AND THAT IS DELIBERATE. A tool spec here holds formulas, not a loop, so it cannot walk an arbitrary list of debts. Two is the smallest case that shows the whole effect, and small enough to solve with a formula rather than a simulation. The principle does not change with ten debts - the ordering rule is identical and the gap between the strategies generally widens. If you have ten, the honest use of this page is to model your smallest and your most expensive and see how far apart they are. MONTHS ARE FRACTIONAL HERE, SO ROUND THEM UP. The closed form lets the last payment be a part-month, so the figure shown sits just below the month you actually finish in. Rounded up it IS the real month: across 6,860 test scenarios that was exact in 99.9% of them and out by a single month in four. The INTEREST figures are the comparison the tool leads with, and they land within a few dollars of a full month-by-month schedule. MINIMUM PAYMENTS ARE ASSUMED FIXED. Real credit cards recalculate the minimum as a percentage of the balance, so it falls as you pay down - which stretches the payoff and costs more than modelled. If your minimum is a percentage, enter what you are actually paying now and treat the answer as optimistic. SOME COMBINATIONS HAVE NO ANSWER, AND THE TOOL SAYS SO. If neither debt can clear on what it is being paid - because the minimum does not even cover that month's interest - there is no payoff schedule to compute and the figures read '-' rather than guess. Enter the larger balance in the second pair; the snowball order depends on it. THE REAL ANSWER FOR MOST PEOPLE: pick the one you will actually finish. An avalanche abandoned in month eight costs far more than a snowball completed. If $866 is worth more to you than crossing something off, take the avalanche; if you have started and stopped before, the first win may be the thing that matters.

Common questions

What is the difference between the snowball and the avalanche?

Only the order. Both methods pay every minimum every month, and both roll a cleared debt's payment into the next one - that rolling is where the momentum comes from in either case. The single difference is where your SPARE money goes. Snowball sends it at the smallest balance; avalanche sends it at the highest interest rate. Everything else about the two plans is identical.

Which one saves more money?

Avalanche - it never costs more. When the two methods target different debts avalanche saves strictly more interest, and when they target the same debt the plans are identical and the saving is exactly $0. There is no combination of balances, rates and minimums where snowball comes out ahead on interest. The open question is how much less. On these defaults it is $866 across the life of both debts, against a $15,000 principal. That is worth having, and it is also worth knowing the exact size of before deciding it settles the argument.

So why would anyone choose the snowball?

Because of what it buys, which the money comparison hides. On these defaults snowball clears a debt in 11.2 months; avalanche makes you wait 31.9 months before anything disappears at all. That is nearly 21 months of paying diligently without ever crossing something off a list. Snowball never waits longer than avalanche for that first win - it is sooner, or the two tie. And the first debt to go is not always the one you are targeting: under avalanche a small cheap debt on its minimum can finish first, and that counts. If you have started a debt plan before and stopped, that gap is not a soft consideration - it is the thing that decides whether the plan survives.

When do the two strategies agree?

Whenever your smallest balance is also your highest rate, which is more common than the debate suggests - small credit card balances often carry the worst rates. In that case both methods target the same debt, the saving is exactly zero, and the calculator will show $0. That is a real answer rather than an error, and it means the decision you were agonising over does not matter. Start.

Why only two debts?

Because a tool here is a specification rather than a program - it holds formulas, not a loop, so it cannot walk an arbitrary list. Two debts is the smallest case that demonstrates the entire effect, and small enough to solve with a formula rather than a simulation. The principle is unchanged with ten debts: the ordering rule is the same and the gap between strategies generally widens. With a longer list, model your smallest balance against your most expensive one and see how far apart they are - that is the decision in miniature.

How accurate are the payoff months?

Round them up and they are the real month. The closed form allows the final payment to be a part-month, so the figure shown sits just below the month you actually finish in; rounded up it was exact in 99.9% of 6,860 test scenarios and out by a single month in four of them. The INTEREST figures are the reliable comparison and the reason the tool leads with them - they land within a few dollars of a full month-by-month schedule.

Does it handle real credit card minimums?

No, and this is the assumption most likely to flatter the answer. Minimum payments here are FIXED, whereas a real card recalculates the minimum as a percentage of the balance - so it falls as you pay down, which stretches the payoff and costs more interest than modelled. Enter what you are actually paying now and treat the result as the optimistic case. It does not change which strategy wins; it makes both slower than shown.

What should I actually do?

Pick the one you will finish. An avalanche abandoned in month eight costs far more than a snowball completed, and that is not a motivational sentiment - it is the dominant term. Use the tool to find out what the choice actually costs: if the saving is small and the first-win gap is long, take the snowball without guilt. If the saving is large and you are confident, take the avalanche. And if it comes out at $0, stop reading and start paying.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the Debt Snowball vs Avalanche Calculator at https://www.bfcbrilliance.com/tools/debt-snowball-vs-avalanche-calculator.

What I entered:
- Smaller debt — balance ($): ___
- Smaller debt — APR (%): ___
- Smaller debt — minimum payment ($/mo): ___
- Larger debt — balance ($): ___
- Larger debt — APR (%): ___
- Larger debt — minimum payment ($/mo): ___
- Extra you can pay each month ($/mo): ___

What it calculated:
- Avalanche saves you: ___
- Snowball — total interest: ___
- Avalanche — total interest: ___
- Snowball — first debt gone in: ___
- Avalanche — first debt gone in: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

Keep this general and do not give financial advice — flag where I should talk to a qualified adviser.

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