How the simulation works
Each month, every debt accrues interest on its remaining balance and receives at least its minimum payment. Any extra budget — your entered extra amount, plus the minimum payments freed up from debts already paid off — goes entirely to whichever debt is highest priority under the chosen strategy, until every debt reaches zero.
Worked example
Suppose you have three debts: Debt A ($1,000 at 6%), Debt B ($8,000 at 24%), and Debt C ($3,000 at 12%), with minimum payments of $50, $150, and $70, plus $200 extra a month:
- Avalanche (pays off B first, the 24% debt): debt-free in about 37 months, ~$3,624 total interest
- Snowball (pays off A first, the smallest balance): debt-free in about 47 months, ~$5,673 total interest
Here avalanche wins on both time and cost because it stops the large, high-rate debt from accruing interest for as long — try adding these three debts above to see the comparison yourself. The gap won't always be this large; it depends on your own numbers.