Debt Payoff Calculator — Avalanche vs Snowball, Real Numbers
List your debts and the monthly amount you can put toward them. The calculator simulates every month, applies your minimums first, throws the remainder at one priority debt, and tells you exactly which month each debt dies and what the whole plan costs in interest. Switch between avalanche and snowball to see the real difference on your own numbers.
Calculator
| Debt | Starting balance | Rate | Cleared |
|---|
The Default Portfolio, Both Ways
The calculator opens with three debts: a $1,200 medical bill at 5% with a $50 minimum, a $9,000 credit card at 24% with a $180 minimum, and a $15,000 car loan at 8% with a $320 minimum. Minimums total $550, so a $900 budget leaves $350 of extra money each month. Here is what each order does with it:
| Order | Debt-free in | Total interest | Cleared first |
|---|---|---|---|
| Avalanche (rate first) | 33 months | $4,393.18 | Credit card, month 21 |
| Snowball (balance first) | 34 months | $4,682.67 | Medical bill, month 4 |
Avalanche finishes one month sooner and pays $289.49 less interest — about 6% of the interest bill. Snowball clears its first account at month 4 instead of month 21, because it goes after the $1,200 medical bill rather than the $9,000 card.
Those two facts are the whole trade. Avalanche saves money and saves a month. Snowball delivers an early win in month 4 that avalanche does not deliver until month 21. Which one you should use depends on whether you can keep paying without that early win.
Why the Saving Is Smaller Than People Expect
Articles often claim the avalanche method saves thousands. That happens when the rates are far apart and the balances are large. On the portfolio above, the gap is $289.49 — real, measurable, but 6% of the interest, not 50%.
Look at why. Both orders finish in about three years and both pay the same minimums every month. The only money that gets routed differently is the $350 of extra: $350 a month for 33 months is about $11,550. Avalanche sends it all to the 24% card first; snowball sends the first months of it to the 5% medical bill. The difference in interest is only what that rerouting costs — the 5% bill only charges 5%, so paying it early saves very little, and the card gets attacked later at 24%. The $289.49 is the cost of those few months of misdirection.
The lesson is not that avalanche is barely worth it. The lesson is that the gap scales with how far apart your rates are. Put a 29% card against a 3% student loan and the gap grows. Put two 18% cards against each other and it collapses to nearly nothing.
The Case Where the Two Orders Are Identical
If one debt is both the highest rate and the smallest balance, both methods attack that same debt first, and the results are identical to the cent. This is more common than people realize: a card that got out of hand is often both the most expensive and, after a few payments, no longer the largest.
When that happens, the choice between methods stops being a mathematical question and becomes purely a matter of what keeps you paying. Take the one that feels winnable.
Why Snowball Still Wins for Some People
On the default portfolio, snowball clears an account in month 4 and avalanche does not clear its first until month 21 — a 17-month gap of watching a balance sit still, which is where many people quit. The $289.49 of extra interest is the price of four account closures instead of one early closure — and someone who quits at month 12 pays far more than $289.49 in interest by never finishing.
So the honest rule: if you will keep paying either way, use avalanche; if an early visible win is what keeps you paying, use snowball. A method you abandon is worse than a method that costs slightly more.
FAQ
How much does the avalanche method actually save?
It depends on how far apart the rates and balances are. On the default portfolio above, avalanche pays $4,393.18 of interest in 33 months and snowball pays $4,682.67 in 34 months — a $289.49 saving, about 6%. When one debt is both the highest rate and the smallest balance, the two methods produce identical results.
Why is avalanche mathematically better?
Interest accrues in proportion to balance times rate. The same extra dollar applied to a 24% balance removes $0.24 of interest per year; applied to a 5% balance it removes $0.05. Avalanche always routes each extra dollar to the highest rate available, so it cannot pay more total interest than any other ordering on the same budget.
When should I use snowball instead?
When motivation is the binding constraint. Snowball clears the $1,200 medical bill in month 4 while avalanche waits until month 21 to clear anything. If seeing accounts disappear keeps you making payments, that is worth more than $289.49. If you will pay regardless, avalanche wins on money.
Do I have to include every debt?
No. A row with a balance of 0 is ignored. Including everything gives the honest total, but the order only matters for the debts you are actively overpaying. A 4% mortgage alongside a 24% card usually belongs in the list only to confirm it lands last.
What if my minimums exceed my budget?
Then there is no extra money to direct and the calculator reports the gap instead of inventing a payoff date. Minimums alone still reduce the debts, but at full interest. Cover the minimums first and send any surplus to the top-priority debt.
Does this account for variable rates or new charges?
No. It assumes fixed rates and no new borrowing, the standard assumption for a payoff projection. A variable-rate balance or a card you keep using will drift from these numbers, so re-run it when the rate moves or the balance goes the wrong way.
Related Tools
For a single loan rather than several, the Loan Payoff Calculator solves the payoff date from your statement balance and payment, and the Personal Loan Payoff Calculator is tuned for small high-rate balances like cards and auto loans. To compare the two orderings in prose, read Debt Snowball vs Avalanche. If a payment you sent did not reduce a balance, read why an extra payment may miss principal. The AmortWise homepage lists every tool, and the terms of use explain how to read these estimates.