Debt Avalanche vs Snowball: What the Difference Actually Costs

How each method actually works

Both methods start the same way: pay the minimum on every debt so nothing goes delinquent, then throw every spare euro at one single target. The only thing that differs is which debt gets the spare money. The avalanche picks the highest interest rate, because that is where the money is leaking fastest. The snowball picks the smallest remaining balance, because that is the debt that will disappear soonest.

When a target is cleared, its minimum payment joins the pot and the whole amount moves to the next debt. That rolling payment is why both methods accelerate: the monthly budget never falls, so each successive debt is attacked by a bigger sum than the last. The name snowball comes from that rolling effect, but the avalanche uses it too.

Why the gap is so small

The avalanche only gains ground while the interest rates differ meaningfully. In the example above, the two big debts sit at 22 and 18 percent — four points apart on balances that clear within two years, which is not enough time for compounding to open a real gap. The 255 saved is real, but it is 3 percent of the balance, not a transformation.

The gap widens in exactly two situations: when one debt carries a rate far above the others, such as a 30 percent store card next to a 6 percent personal loan, and when the total takes many years rather than months to clear. If neither applies to you, treat the choice as a matter of temperament rather than of arithmetic.

The case for the mathematically worse method

Clearing a whole debt is a visible finish line, and finishing something makes people keep going. That is the entire argument for the snowball: it front-loads completed debts, so the plan produces early proof that it works. Consumer research on repayment behaviour has found that people who close small balances first are more likely to stay with the plan, and a plan abandoned in month six costs far more than the 255 the avalanche would have saved.

A practical compromise exists: run the avalanche, but if one debt is small enough to clear within a month or two, take it out first anyway. You get one early win, the rolling payment grows sooner, and the interest cost of the detour is a few euros.

Frequently asked questions

Does either method work if I only pay the minimums?

No. Both methods are ways of allocating money above the minimums, so with no surplus there is nothing to allocate and neither applies. If your budget only covers the minimums, the problem to solve first is the budget or the interest rate, not the repayment order.

Where do 0 percent promotional balances fit?

Outside both rankings. A 0 percent balance costs nothing while the promotion lasts, so it belongs last — until the end date, when the rate jumps to the standard one and it usually becomes the highest rate you hold. Diarise the expiry and move it to the front of the queue a few months before.

Should I keep an emergency fund while repaying?

Keep a small one. Sending every spare euro to the debt is optimal on paper, but a single unexpected bill then goes back on the card at 20 percent and undoes months of progress. A modest buffer of one month of essential spending costs a little interest and stops the plan collapsing at the first surprise.