The two methods
Avalanche pays the highest interest rate first, while covering minimums on everything else. It is mathematically optimal — it always costs the least in total interest and usually clears fastest.
Snowball pays the smallest balance first. It costs more, sometimes considerably, and it closes individual accounts sooner.
Enter your debts above and the calculator runs both. Where the smallest balance also carries the highest rate the two are identical; where they diverge, the gap is worth seeing before deciding.
Why the worse method often wins
Avalanche is better on paper and snowball is frequently better in practice, which is an uncomfortable but well-documented result.
Research into actual repayment behaviour has found people are more likely to complete a snowball plan. The reason is motivational: closing an account entirely is a visible, definite win, and it arrives sooner. Avalanche can mean grinding away at a large high-rate balance for a year with nothing apparently changing.
So the choice is not simply "which is optimal" but "which will I finish". If the avalanche saving on your numbers is small, take the snowball and its momentum. If it is large, the arithmetic deserves to win.
Fix the rate before optimising the order
Both methods take your interest rates as given. Often you can change them, and doing so beats any reordering.
A balance transfer to a 0% introductory offer eliminates interest for a window, though transfer fees of 1–3% apply and the post-promotional rate is usually high. It works only if you clear the balance inside the window.
A consolidation loan at a lower rate converts several revolving debts into one fixed term with a definite end date. The end date is worth as much as the rate cut, because revolving debt has no natural conclusion.
And asking your existing lender for a lower rate succeeds more often than people expect, particularly with a clean payment history and a competing offer to cite.
The rule underneath all of it
Your total payment must exceed the total monthly interest, or the balances grow no matter how you order them. The calculator flags this rather than producing a meaningless number.
Once that condition is met, three things matter in order: the size of the payment, whether the rates can be reduced, and only then the ordering. People often spend the most time on the ordering, which is the smallest of the three levers.
It is also worth stating plainly that clearing debt at 24% is a guaranteed, tax-free 24% return. No investment reliably matches that, which is why high-rate debt comes before investing and before overpaying a mortgage.
Frequently asked questions
What is the difference between the debt snowball and avalanche?
Avalanche pays the highest interest rate first and always costs the least in total interest. Snowball pays the smallest balance first, costs more, but closes accounts sooner. Both cover minimums on everything else.
Which debt payoff method is better?
Avalanche is mathematically optimal, but research on actual repayment behaviour finds people are more likely to finish a snowball plan, because closing accounts provides visible progress. If the avalanche saving on your numbers is small, the snowball's momentum is worth more.
What if my payment does not cover the interest?
The balances grow regardless of the order you pay them in, and no strategy helps. The total payment must exceed the total monthly interest before any repayment plan can work.
Should I pay off debt or invest?
Clearing debt at 24% is a guaranteed, tax-free 24% return, which no investment reliably matches. High-rate debt comes before investing and before overpaying a mortgage. Keep a minimal emergency buffer alongside it so a surprise expense does not push you back onto the card.