If you carry balances on more than one credit card, you have probably encountered the avalanche versus snowball debate. Financial content tends to treat this as an obvious choice with a clear right answer. The avalanche method (targeting highest APR first) is mathematically optimal, so you should use it. Or: the snowball method (targeting smallest balance first) produces psychological wins that improve adherence, so you should use it. The real answer depends on your specific numbers. The difference in total interest between the two methods varies from negligible to substantial depending on your balances and APR distribution. For some card portfolios, avalanche saves hundreds of dollars. For others, the savings are under $50 across the full payoff period. Calculating the actual difference for your situation is a five-minute exercise that tells you exactly what the choice costs you - and in some cases, removes the dilemma entirely. This guide walks through the calculation step by step.…