Debt Payoff Calculator
Avalanche against snowball, simulated month by month, with the interest each one costs and how much the difference is actually worth.
Debts 4
Total owed $14,000.00
Minimum payments $343.00 a month
Extra a month $250.00
Paying in total $593.00 a month
Interest a month, at the start $191.92
Overdraft $1,500.00 at 39.9%, minimum $40.00
Store card $900.00 at 29.9%, minimum $30.00
Credit card $4,200.00 at 22.9%, minimum $105.00
Car loan $7,400.00 at 6.4%, minimum $168.00
Avalanche, highest rate first
months 28
years 2.3
interest paid $2,206.00
total paid $16,206.00
Snowball, smallest balance first
months 28
years 2.3
interest paid $2,262.39
total paid $16,262.39
The difference
avalanche saves $56.38
and finishes in the same month
first debt cleared month 6 on avalanche, month 4 on snowball
Your order, avalanche
Overdraft cleared in month 6
Store card cleared in month 9
Credit card cleared in month 19
Car loan cleared in month 28
What the $250.00 a month is doing
without it 70 months, $9,688.40 of interest
with it 28 months, $2,206.00 of interest
saves $7,482.40 and 42 months
return on that money 106.9% of what you put in
Avalanche saves $56.38 of interest here, and both plans finish in the
same month. It is always at least as cheap, because interest is charged
on balances and the highest rate costs the most to carry.
Snowball clears the first debt in month 4 against month 6 for avalanche.
That is the whole case for it: research on people actually finishing a
plan favours the visible early win, and a cheaper plan you abandon costs
more than an expensive one you finish.
The difference is $56.38, which is 0.4% of what you owe. That is small
enough that the plan you will stick to is the right one.
Pay the minimum on everything. Missing a minimum triggers a fee, often a
penalty rate, and a mark on your credit file, all of which cost more
than any amount of optimisation gains. The extra goes to one target; the
minimums are not optional.
The rate on the debt is the return on paying it. Clearing a 22 percent
card is a guaranteed 22 percent return, tax free, which beats almost any
investment. Above about 8 percent, paying the debt down is usually the
better use of the money than investing it.
A balance transfer or consolidation changes the arithmetic more than the
order does. A zero-percent transfer for eighteen months, with the fee
counted, can save more than any payoff strategy, and the trap is
spending on the cleared card.
Interest is charged monthly here, which matches how a card statement
works. A card that compounds daily costs slightly more than this shows,
and the annual rate quoted on a card is the APR, which already includes
that compounding.
This is arithmetic, not financial advice. If the minimum payments are
already unaffordable, the useful next step is a free debt advice service
rather than a calculator: they can negotiate rates and freezes that no
payment plan can achieve.
Output is valid and updates as you type.
Fix the highlighted fields to update the output.
Avalanche pays the highest interest rate first. Snowball pays the smallest balance first. Avalanche is always at least as cheap, because interest is charged on balances and the most expensive one costs the most to carry.
On the four debts below, avalanche saves $56 in interest and both plans finish in the same month. That is the honest answer to the argument: at this size, the difference is a rounding error, and the plan you will actually finish is worth more than the one that is theoretically optimal. On other numbers the gap runs to thousands, and then the arithmetic wins.
Both are simulated month by month rather than approximated, because minimum payments against compounding interest with a rolling extra payment has no tidy formula.
How to use
- List the debts as
name : balance : annual rate : minimum payment, one a line. - Put in whatever extra you can pay each month.
- Read the difference, then pick the plan you will stick to.
Example
Total owed $14,000.00
Minimum payments $343.00 a month
Extra a month $250.00
Interest a month, at the start $191.92
Overdraft $1,500.00 at 39.9%, minimum $40.00
Store card $900.00 at 29.9%, minimum $30.00
Credit card $4,200.00 at 22.9%, minimum $105.00
Car loan $7,400.00 at 6.4%, minimum $168.00
Avalanche, highest rate first
months 28
interest paid $2,206.00
Snowball, smallest balance first
months 28
interest paid $2,262.39
The difference
avalanche saves $56.38
and finishes in the same month
first debt cleared month 6 on avalanche, month 4 on snowball
What the $250.00 a month is doing
without it 70 months, $9,688.40 of interest
with it 28 months, $2,206.00 of interest
saves $7,482.40 and 42 monthsThe extra $250 a month matters roughly a hundred times more than the choice of strategy. That is the finding worth acting on.
Pitfalls
Pay every minimum. Missing one triggers a fee, often a penalty rate, and a mark on your credit file, all of which cost more than any optimisation. The extra goes to one target; the minimums are not optional.
The rate on a debt is the return on paying it. Clearing a 22 percent card is a guaranteed 22 percent return, tax free, which beats almost any investment. Above roughly 8 percent, paying down usually beats investing.
The snowball’s advantage is behavioural and real. Research on people actually finishing a payoff plan favours the visible early win. A cheaper plan you abandon in month four costs more than an expensive one you complete.
A balance transfer changes more than the order does. A zero-percent transfer for eighteen months, with the fee counted, can save more than any strategy. The trap is spending on the newly cleared card.
Check whether the minimum falls as the balance does. Most cards set the minimum as a percentage of the balance, so it shrinks as you pay, which stretches the term. This model holds the minimum constant, which is what you should do anyway: keep paying the original amount.
Interest here is monthly. That matches a card statement. A card compounding daily costs slightly more than shown, and the APR quoted on the card already includes that compounding.
If the minimums are already unaffordable, this is the wrong tool. A free debt advice service can negotiate rate freezes and payment plans that no calculator can produce, and using one is not a failure.
Compatibility
Arithmetic in the browser: nothing is uploaded and nothing is stored, which matters for personal figures.
The simulation charges interest on the balance carried into each month, then pays every minimum, then puts the extra plus any freed-up minimums into the target debt. That is what both strategies do in practice, and it is why the payment accelerates as debts clear.
Where no minimum is given, one percent of the balance plus a month’s interest is assumed, which is the shape most card issuers use. A plan whose total payment does not cover the monthly interest is refused with an explanation rather than run for a hundred years.
The test suite asserts that avalanche never charges more interest than snowball, that avalanche clears the highest-rate debt first, that snowball clears the smallest balance first, and that an impossible plan terminates rather than looping.
This is arithmetic, not financial advice, and it does not know about fees, promotional rates that expire, or what happens to your credit file.