Snowball vs Avalanche: Which Clears Debt Faster?

There are two ways to order a debt payoff, and the argument between them is usually conducted without numbers. Here it is with numbers.

The setup: $20,400 across three debts, with $750 a month to put against them.

Debt	Balance	Rate	Minimum
Store card	$1,800	24.99%	$45
Credit card	$7,400	19.99%	$185
Car loan	$11,200	7.50%	$260

How both methods work

The mechanics are identical. Every month, interest accrues on each balance, every debt receives its minimum, and whatever is left of the budget goes entirely to one target debt. When that debt clears, its minimum joins the pool attacking the next.

That rollover is why payoff accelerates. The first debt is slow; the last one falls in weeks.

The two methods differ in one respect only: which debt is the target.

• Avalanche targets the highest interest rate.
• Snowball targets the smallest balance.

What the difference costs

	Avalanche	Snowball
Months to debt-free	32	32
Total interest	$3,459	$3,459

Nothing. On these balances the two methods are not merely close — they are identical, month for month and cent for cent.

Why they are identical here

Because the store card is both the smallest balance and the highest rate. Both methods target it first, then the credit card, then the car loan. The orderings agree completely, so there is nothing to choose between them.

This is more common than the debate suggests. Small debts are often store and credit cards, which are also the expensive ones; large debts are often car loans and mortgages, which are cheap. When that holds, the argument is moot.

When they genuinely diverge

The two methods only disagree when a small debt is also a cheap one. Put $3,000 at 5% against $9,000 at 24%, with $700 a month:

	Avalanche	Snowball
Months	20	21
Total interest	$1,875	$2,585

Now the avalanche saves $710 and finishes a month sooner, because the snowball spends its early months clearing a debt that was barely costing anything while the expensive one kept compounding.

The lesson is not "always pick one". It is that you cannot know the cost without running your own balances — it may be $710, or it may be exactly zero. Run them through the debt payoff calculator, which computes both.

When the snowball is the right answer

A 2015 Harvard Business School study found people were more likely to stay with the snowball through to completion. That is not irrationality to be corrected — it is a real property of the method, and a plan you abandon in month eight saves nothing at all.

So the decision rule is straightforward:

• If the gap is small or zero — as it is in the first example — take the snowball. The motivation is free.
• If the gap is large — hundreds or thousands, as in the second — take the avalanche, and find your motivation somewhere else.

The thing that matters more than either

Neither method is the biggest lever. The budget is.

On the first set of debts, raising the monthly payment from $750 to $900 clears them in 26 months instead of 32 and saves $775 in interest — against the $0 the ordering decision was worth there.

Ordering is worth getting right because it is free. But if you are choosing between spending an evening optimising the order and spending it finding another $150 a month, the second is worth far more.

One case where neither helps

If your combined minimums exceed what you can pay, no ordering helps — the balances grow whatever you choose. That is a different problem, and the answers to it are a hardship arrangement with the lender, a non-profit credit counselling service, or a consolidation loan at a lower rate. All three are ordinary, and asking early is considerably better than asking after a default.