The short answer
Avalanche kills the most-expensive debt first — it saves the most interest. Snowball kills the smallest balance first — early wins fuel momentum. Pick avalanche if you'll stick with the plan whatever the math; pick snowball if you've quit plans before.
How each works
Avalanche: list debts by interest rate, throw every spare euro at the highest. When it's gone, roll the payment into the next. Snowball: same idea, but order by balance, smallest first.
A worked example
€15,000 spread across three cards (€2k @ 12 %, €5k @ 18 %, €8k @ 22 %), about €575/month total. Both strategies finish within four months of each other — but avalanche saves about €1,300 in interest. Snowball clears its first card in 7 months; avalanche, in 24. The trade is real money for early dopamine — and if dopamine is what keeps you paying, that isn't optional.
So which?
Avalanche if motivation isn't the bottleneck. Snowball if it is.
Try it on your numbers
Open the debt-payoff calculator, paste your balances and rates, toggle the strategy — the chart shows the gap.