The debt avalanche attacks your highest interest rate first — the mathematically fastest, cheapest way out of debt. List up to four debts, add any extra payment, and see your debt-free date, the interest you'll pay, and exactly how much the avalanche saves you versus paying only minimums.
Highest interest first
Enter each debt's balance, APR, and minimum monthly payment. Leave a balance blank to skip that row.
If you want to pay the least interest and get out of debt in the shortest possible time, the avalanche is the answer. The logic is pure arithmetic: interest is the enemy, and the debt charging you the highest rate is bleeding you fastest. So you make minimum payments everywhere, then throw every extra dollar at the highest-APR debt until it's destroyed — regardless of how big or small its balance is. Then you move to the next-highest rate, and so on down the line. Every month you do this, you're starving the most expensive debt of the fuel it needs to grow.
Compared to the snowball method, which targets the smallest balance first for motivation, the avalanche almost always wins on the numbers. By eliminating high-interest debt early, you stop the compounding that quietly inflates what you owe, which means more of every future payment goes to principal instead of the lender's pocket. Over a few years and several debts, the savings can run into thousands of dollars and shave months off your timeline. This calculator runs the entire month-by-month plan, rolls each freed-up payment onto the next target, and shows you precisely how much the avalanche saves against the do-nothing-extra baseline.
The avalanche's only real weakness is psychological. If your highest-rate debt also happens to carry a large balance, you might grind away for many months before you see a single account hit zero, and for some people that lack of early wins saps the willpower to continue. Be honest with yourself: if you're motivated by saving the most money, the avalanche is unbeatable. If you need visible progress to stay in the game, the snowball's quick knockouts may be worth a small premium. Both beat doing nothing — the worst plan is the one you abandon.
Targeting the highest APR first stops the fastest-growing interest, saving the most money overall.
The avalanche is mathematically optimal — it always pays the least total interest of any ordering.
If your priciest debt is large, early wins are slower. Stay disciplined and the savings are worth it.
The avalanche method orders debts by interest rate, highest first, paying minimums on everything and directing all surplus at the most expensive balance. It is provably the cheapest strategy — no other ordering produces less total interest — because interest accrues in proportion to rate, so removing the highest rate first removes the fastest-growing debt. Its weakness is behavioural rather than mathematical: if the highest-rate debt is also the largest, the first payoff can be many months away, and plans that produce no visible wins are the ones people abandon.
Order: sort debts by APR descending, regardless of balanceSurplus = Total available − Sum of all minimumsWhen a debt clears, its full payment rolls onto the next in orderTotal interest is minimised by this orderingwhere:
Assumptions: Assumes no new borrowing and that freed payments are genuinely redirected. Compare against the snowball method, which orders by balance and finishes marginally later but delivers earlier psychological wins.
Order by rate and watch the rollover build.
ResultDebt-free in ~31 months — about $2,750 of interest
The snowball ordering here — smallest balance first — would clear Loan C early for a quick win but cost roughly $190 more in total. Whether that $190 is worth paying for motivation is a genuine judgement, not an error; the avalanche is simply the arithmetic optimum.