The debt payoff calculator.

Debt avalanche always pays the least total interest. By targeting the highest-APR balance first, every extra dollar goes to where it cuts the most interest. Snowball pays the lowest balance first instead, which costs more in interest but produces faster early wins. Snowball is the right choice if you need the motivation; avalanche is the right choice if you can stay disciplined for the long haul. Run both above and pick the one whose numbers you can actually live with.

Every active debt accrues interest at APR ÷ 12 on its current balance. Then minimum payments are applied to all debts, and any extra payment plus freed-up minimums are poured into the priority debt (highest APR for avalanche, lowest balance for snowball). Once a debt hits zero, its minimum payment rolls into the next priority — that "snowball effect" applies to both strategies.

The debt grows instead of shrinks. The calculator flags any debt where the minimum is below the monthly interest charge. Common with maxed-out credit cards at 24%+ APR — even paying the minimum keeps you running in place. Your real options are negotiating the rate, transferring to a 0% card, or paying more than the minimum.

Pay off any debt above ~6-7% APR before investing — that's a guaranteed return higher than the long-run stock market average. For lower-rate debt (mortgages, federal student loans at 4-5%, auto loans at 6%), most FIRE planners run them in parallel with investing. Always capture the full employer 401(k) match first regardless of debt — it's free money you can't recoup.

A 0% intro APR balance transfer card (typically 12–21 months) can save thousands on high-interest credit card debt — but only if you actually pay it off before the intro period ends. Otherwise you owe a 3-5% transfer fee plus a snap-back to a higher rate. Run the math by reducing the credit card APR to 0 in the calculator above to see how much faster you'd hit zero.

A consolidation loan replaces multiple debts with a single fixed-rate personal loan. The calculator above handles that by collapsing your debts into a single row at the new rate. Consolidation works when the new rate beats the weighted-average rate of your existing debts, but it can hurt if it extends the term — paying 6% over 10 years costs more than 12% over 3 years.

Faster in months and cheaper in total interest, yes — but the difference is often smaller than people assume. For typical mid-range debt loads ($20K–60K with 2–4 debts), avalanche typically saves $300–2,000 in interest and 1–6 months. The bigger lever is almost always the extra monthly payment, not the strategy.