Free tool
Debt payoff calculator
Put your debts in once. Both plans get solved to the last dollar, so you can see what the avalanche saves you before you commit to the harder one.
The short version: the avalanche costs less, always, because attacking the highest rate first means less interest accrues. The snowball clears a whole debt sooner, which is worth real money if it is the thing that keeps you paying. The gap between them is different for every set of balances, so put yours in and look at it rather than taking anyone's word for it.
Your debts
On top of every minimum. This is the only number you control.
Used for the debt-free date.
Debt-free in
—
Fill in at least one balance, rate, and minimum.
Avalanche
Highest rate first
- Months
- —
- Debt-free
- —
- Interest
- —
- Total paid
- —
Snowball
Smallest balance first
- Months
- —
- Debt-free
- —
- Interest
- —
- Total paid
- —
| Month | Paying off | Interest | Principal | Remaining |
|---|
How this works out the answer
Every month, interest is added to each balance at its APR divided by twelve. Then the payments go out. Each debt receives its minimum, and whatever is left of your total monthly payment lands entirely on one target: the highest rate under the avalanche, the smallest balance under the snowball.
balance = (balance x (1 + APR/12)) - minimum - (leftover, if this is the target debt)
The part people miss is what happens when a debt clears. Its minimum does not go back into your spending. It joins the leftover and lands on the next target, so the amount attacking your debt grows every time one dies. That rollover is the whole engine, and it is why both methods finish far sooner than paying minimums forever.
One case breaks every plan. If a minimum payment is smaller than one month of interest on that balance, the balance grows no matter what order you choose. The calculator flags that row when it sees it. That debt needs a bigger payment or a lower rate before any of this matters.
Testing a spreadsheet you already have? The four checks that separate a working payoff engine from one that prints a plausible date are in four things a debt payoff spreadsheet has to get right.
Questions people ask
Is the snowball or the avalanche better?
The avalanche costs less or the same, never more. The snowball clears an individual debt sooner. Look at the gap in your own numbers above: if it is a few hundred dollars, take the snowball and take the momentum. If it is thousands, the avalanche is worth the patience.
Does the extra payment really matter that much?
It is the only lever you have. Balances, rates, and minimums are set by your creditors. Change the extra payment field and watch the date move, because every dollar of it goes to principal on the target debt rather than to interest.
What if my rate changes?
This assumes a fixed APR, which is right for car loans and most student loans and wrong for a variable-rate card. If your rate moves, come back and rerun it. The spreadsheet is better for that because it keeps your figures between visits.
Do you store what I type?
No. This runs entirely in your browser. Nothing is sent anywhere, nothing is saved, and closing the tab loses it. That is also why the spreadsheet exists.
Educational tool, not financial advice. It assumes fixed rates, no new charges on any balance, no fees, and that you make every payment on time. Real accounts have late fees, promotional rates that expire, and minimums that change with the balance. Confirm anything that matters with your lender.
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