How much money does the debt avalanche method actually save versus the snowball?

The avalanche pays your highest-APR debt first, so mathematically it always costs the least interest and finishes fastest. The snowball pays the smallest balance first for quick wins. The gap between them depends on how different your rates are. If one card is 28% and another is 15%, avalanche can save hundreds to a few thousand dollars over the payoff period. If all your rates are similar, the difference is trivial and you should just pick the one you'll stick with.

A 2016 study out of the Kellogg School and other behavioral research found people are more likely to stay motivated and finish with the snowball. The best method is the one you actually complete. Model both with the Debt Payoff Calculator at wealthserene.com/tools/debt-payoff before deciding.