Debt Payoff Planner (Snowball & Avalanche)
Plan the fastest or cheapest way out of multiple debts.
Total you can put toward all debts each month.
3 debts in this plan.
Debt-free in (avalanche)
- Total interest paid
- $3,853.73
- Total paid
- $21,653.73
- Snowball time
- 4 yr 1 mo
- Snowball interest
- $3,941.77
- Interest saved vs. that
- $88.04
Interest accrues monthly on each balance; every surplus dollar rolls onto the top-ranked debt. Estimate only.
How the debt payoff planner works
The planner simulates your debts month by month under a single fixed monthly budget. Each month it does four things in order: it accrues interest on the opening balance of every debt, ranks the debts by your chosen strategy, pays each debt its minimum in rank order, then cascades any leftover budget into the same ranked targets within the same month. That roll-over is the engine of both methods: once a debt is cleared, the money that was paying it automatically flows to the next target.
Interest for a debt in a given month is interest = balance * (APR / 100 / 12), rounded to the cent. The only thing that changes between strategies is the ranking. Snowball orders active debts by balance ascending (smallest first). Avalanche orders them by APR descending (highest rate first). The planner runs both and reports the payoff month count and total interest for each, so you can compare them side by side.
Worked example
Two debts, with a monthly budget of $500:
- Debt P: $1,000 balance, 5% APR, $25 minimum
- Debt Q: $1,500 balance, 24% APR, $40 minimum
Snowball pays the smaller balance (P) first. In month 1, P accrues $4.17 interest and Q accrues $30.00. P takes its $25 minimum plus the surplus ($435), so P gets $460 and Q gets its $40 minimum. P clears in month 3, after which the full $500 floods Q. The result:
| Strategy | Payoff | Total interest | Total paid |
|---|---|---|---|
| Snowball | 6 months | $133.09 | $2,633.09 |
| Avalanche | 6 months | $84.81 | $2,584.81 |
Avalanche instead floods Q (24% APR) first: in month 1, Q receives $475 and P receives its $25 minimum. Q clears in month 4, then the budget shifts to P. Both methods finish in 6 months here, but avalanche pays $48.28 less interest because it shrinks the expensive 24% balance faster. Total paid in each case equals the $2,500 principal plus the interest.
How to use it
- Enter every revolving or installment debt with its current balance, APR, and required minimum payment.
- Set the monthly budget to the total you can put toward all debts combined, including the minimums.
- Compare the two strategies. If the interest gap is small, snowball’s quicker first win may be worth it; if the gap is large, avalanche saves real money.
- If you see infeasible, your budget is below the combined minimums (or below the interest on a single debt). Increase the budget until both strategies pay off.
- Re-run it whenever a balance, rate, or your budget changes, since a higher budget shortens the payoff and cuts interest on both paths.
Limitations
This is a planning estimate, not financial advice. It assumes fixed APRs, fixed minimum payments, no new charges, no fees or penalty rates, and that you pay the full budget every month on time. Real cards may change rates, charge late fees, or apply payments differently, and promotional 0% windows that expire are not modeled. Use the result to choose a strategy and target, then confirm the exact terms with your lender.
Frequently asked questions
Which is better, the snowball or the avalanche method?
Avalanche almost always costs less interest, because it attacks the highest-rate debt first. Snowball can clear a small balance sooner, which some people find motivating. This planner runs both at once so you can see the exact interest difference and decide whether the motivation is worth the extra cost.
What does 'infeasible' mean in the results?
It means your monthly budget cannot cover the required minimum payments, or on a single debt the interest each month is larger than your budget, so the balance never shrinks. Raise the monthly budget or lower a balance and recalculate. With one debt at 30% APR and a balance of $500, the monthly interest is $12.50, so a budget of $10 will never make progress.
Does the order I enter my debts matter?
Only as a tie-breaker. When two debts have the same balance (snowball) or the same APR (avalanche), the one you entered first is paid first. Otherwise the strategy decides the order, not your input sequence.
Why might both strategies finish in the same number of months?
When your budget is large relative to the debts, both methods clear everything within the same month count, but they still differ in total interest. The avalanche path keeps the high-rate balance smaller for longer, so it accrues less interest even when the payoff date matches.
Does this assume my interest rates stay fixed?
Yes. The planner holds each APR constant for the whole simulation and applies it monthly. Variable-rate cards, promotional 0% periods that expire, and new charges are not modeled, so treat the result as a snapshot of today's terms.