Two cards. Same total debt, same monthly budget. The only difference is which card gets the extra money first. Here is what the arithmetic actually says — no advice, just the numbers, so you can run your own.
The setup
- Card A: $900 at 15.9% APR
- Card B: $3,200 at 24.9% APR
- Total: $4,100
- Monthly budget: $230, fixed, no new charges
Assumptions, stated so you can check my math: interest accrues monthly at APR / 12. Each card's minimum payment is the greater of $25 or 2% of its balance. After minimums, every spare dollar goes to one target card until it is gone, then to the other.
Snowball: smallest balance first
Extra money goes to Card A ($900) first.
- Card A is gone in month 6. One card closed, one to go.
- Debt-free in 23 months.
- Total interest: $1,038. Total paid: $5,138.
Avalanche: highest interest first
Extra money goes to Card B (24.9%) first.
- Card A stays open until month 22 — you close nothing until the very end.
- Debt-free in 22 months.
- Total interest: $918. Total paid: $5,018.
The difference
| Snowball | Avalanche | |
|---|---|---|
| Months to debt-free | 23 | 22 |
| Total interest | $1,038 | $918 |
| Total paid | $5,138 | $5,018 |
| First card closed | Month 6 | Month 22 |
Avalanche wins on math by $120 and one month. Snowball wins on momentum: a closed account in month 6, sixteen months earlier than avalanche's first closure.
That is the whole trade. $120 buys the early win; the early win costs $120. Which one matters more depends on what keeps you paying in month 9, when neither method feels fast.
Same debts, smaller budget
At $130 a month instead of $230, the gap widens:
| Snowball | Avalanche | |
|---|---|---|
| Months to debt-free | 51 | 49 |
| Total interest | $2,478 | $2,247 |
Same $4,100, same two cards — $2,478 of interest instead of $918, just because the monthly payment dropped by $100. The payment size moves the total far more than the payoff order does. (That matches the earlier minimum-payment example: $4,100 at 18.9% takes 44 months and $1,612 of interest at $130 a month, versus 22 months and $751 at $230.)
Run your own numbers
I ran these on the same model behind a free payoff calculator I built: https://alapha888.github.io/irregular-income-debt-baseline/ — enter your balances, APRs, and monthly payment and it shows the months and interest. No signup, no email.
The model is simple on purpose. Real cards vary — minimum-payment formulas, penalty APRs, promotional rates — so treat this as an illustration, not a plan. If the numbers change your mind about anything, that is the point: the arithmetic is checkable, and it is yours to redo.
Top comments (0)