Debt Payoff Calculator
Enter your debts, choose snowball or avalanche, and see your debt-free date, total interest, and what an extra monthly payment changes.
Your debts
How the two strategies differ
Both methods have you pay minimums on everything and aim all extra money at one target debt. They differ only in which debt gets targeted. Avalanche attacks the highest interest rate first, which is mathematically optimal — every dollar goes where it stops the most interest. Snowball attacks the smallest balance first, which produces quick wins: debts disappear early, the list shrinks, and that momentum keeps real people going.
The honest answer about which is better: avalanche saves more money, snowball finishes more often. The dollar difference between them is frequently smaller than people expect — run both above and see. Our article snowball vs. avalanche works through a full example, and if any of your debts are credit cards, the minimum payment trap shows why "minimums only" is the one strategy that always loses.
How the simulation works
Each simulated month, every balance accrues one month of interest (APR ÷ 12), minimum payments are applied, and your extra payment goes to the target debt under your chosen strategy. When a debt is paid off, its minimum payment is freed up and your extra pool effectively grows — the "snowball" effect both strategies share. The comparison figure re-runs the same debts with no extra payment, so you can see exactly what your extra money buys.
Worked example
Take the defaults above: a $5,000 credit card at 24.99% APR ($150 minimum) and a $12,000 car loan at 7.5% ($320 minimum), plus $200 extra per month. Avalanche targets the card first — at nearly 25%, it's generating about $104 of interest in the first month alone. The card dies in roughly 17 months, then the full $350 (card minimum + extra) piles onto the car. Debt-free in about 3 years, versus about 4 with minimums only, and thousands less interest paid.
In this example snowball and avalanche pick the same first target (the card is both the smallest balance and the highest rate), which happens often in real life — one more reason the war between the two methods matters less than the extra $200.
Questions people ask
Should I save or pay off debt first?
A small emergency fund first — even $1,000 — so that a surprise doesn't go straight back on the card. Then attack the debt, then build the full cushion. Our emergency fund calculator helps size both stages.
Do balance transfers change the strategy?
A 0% transfer can genuinely help, but treat the transfer fee (typically 3–5%) as interest, and have a plan for the balance before the promo rate ends. A transfer without a payoff plan usually just relocates the problem.
What counts as "extra payment"?
Anything above the sum of your minimums. Even $50 matters more than it looks, because it compounds: every dollar of principal killed today stops generating interest every month afterward.