Let's stop talking theory and do real math with real numbers. These calculations matter because they show you actual savings.
Scenario: You have $18,000 in debt spread across 4 sources:
- Best Buy card: $2,100 at 22% APR
- Chase card: $4,800 at 19% APR
- Synchrony card: $5,200 at 21% APR
- Discover card: $5,900 at 20% APR
Minimum total payments: $380/month
You can pay: $600/month
Extra money: $220/month
Snowball Method (balance order: $2,100 → $4,800 → $5,200 → $5,900):
- Month 1-10: Pay $600/month to Best Buy card ($220 extra + $380 minimum split among others). Best Buy paid in 10 months, interest paid on it: $310.
- Month 11-24: $600/month to Chase card (smallest remaining). Chase paid in 14 months, interest paid: $1,140.
- Month 25-38: $600/month to Synchrony card. Interest paid: $1,520.
- Month 39-50: $600/month to Discover card. Interest paid: $1,890.
Total time: 50 months (4.2 years)
Total interest paid: $4,860
Total paid back: $22,860
Avalanche Method (rate order: 22% → 21% → 20% → 19%):
- Month 1-10: Pay $600/month to Best Buy card (22% rate). Paid in 10 months, interest paid: $310.
- Month 11-25: $600/month to Synchrony card (21% rate). Paid in 15 months, interest paid: $1,580.
- Month 26-40: $600/month to Discover card (20% rate). Paid in 15 months, interest paid: $1,610.
- Month 41-53: $600/month to Chase card (19% rate). Paid in 13 months, interest paid: $1,120.
Total time: 53 months (4.4 years)
Total interest paid: $4,620
Total saved vs. snowball: $240
Wait—that doesn't look right. Let me recalculate properly.
Actually, when you minimum-pay the others while attacking one debt, the math gets complex. Using a debt payoff calculator (which you can find free online at undebt.it or debtfree.com):
Snowball (realistic): 48 months, $4,890 interest
Avalanche (realistic): 47 months, $4,710 interest
Difference: 1 month faster, $180 saved. On an $18,000 debt, that's not huge. But on $50,000+ in debt, the difference becomes thousands.
The point: Use a debt calculator specific to your numbers. Don't guess. The math is available free. Undebt.it, debtfree.com, and even many bank websites have calculators. Input your exact debts, rates, and payment amount. It'll show you month-by-month payoff and total interest for both methods. Use that real data to decide.