Debt payoff calculator
Choose a payoff order and keep the budget visible.
- Formula and assumptions shown
- Table and CSV export
- Runs in your browser
Inputs
Result
Assumptions used
Enter your numbers to see an estimate.
Assumptions and methodology
Balance over time
Monthly viewChart data will appear here as a text summary.
How it works
Enter each balance, annual rate, and minimum payment, then add any extra amount to the starting monthly budget. Every active debt receives its minimum first; once a debt is cleared, its freed minimum rolls into the remaining strategy budget.
Avalanche sends the available amount to the highest rate first, which generally minimizes modeled interest. Snowball sends it to the smallest balance first, which can reduce the number of open debts sooner. Both are estimates, not instructions from a lender.
The two strategies diverge only when ordering by balance and ordering by rate disagree at some point. When the next debt to target is always both the smallest and the highest-rate one left, avalanche and snowball send extra money to the same place and produce identical results. When they differ, weigh the modeled interest difference against how soon each plan clears its first balance.
Assumptions
- The starting monthly budget is all listed minimum payments plus the fixed extra amount; it stays constant as debts are cleared.
- Payments are modeled monthly. Interest is approximated as annual nominal rate divided by 12; real credit cards may accrue interest daily.
- Minimums are paid before strategy-directed extra money, and a cleared debt's unused minimum rolls to the next target.
- The model supports a maximum of 600 modeled months; it excludes fees, new charges, changing rates, penalties, and lender-specific payment allocation.
Worked example
Three debts with $300 extra
With a $3,500 credit card at 22.9% ($100 minimum), a $12,000 auto loan at 7.5% ($300 minimum), and a $9,000 student loan at 5.2% ($200 minimum), the $900 monthly budget clears everything in 30 months under either strategy. Avalanche pays the card off in month 10 and the auto loan in month 25, with $2,328.94 of modeled interest. Snowball also clears the card first, in month 10, but then targets the smaller student loan, which it clears in month 23; it pays $2,441.92 of interest, $112.98 more. If the student loan were $18,000 instead, the auto loan would be both the smaller and the higher-rate of the two debts left after the card, so both strategies would follow the same order and cost $3,850.96 over 42 months.
Step by step
- Set the monthly budget. The minimums total $100 + $300 + $200 = $600. Adding the $300 extra gives a $900 monthly budget that stays the same until every debt is paid.
- Charge the first month’s interest. Card: $3,500 × 22.9% ÷ 12 = $66.79. Auto loan: $12,000 × 7.5% ÷ 12 = $75.00. Student loan: $9,000 × 5.2% ÷ 12 = $39.00.
- Pay minimums, then direct the extra (avalanche). Each debt gets its minimum and the $300 extra goes to the highest rate, the 22.9% card. The card receives $400 in month 1 and its balance falls to $3,166.79.
- Roll freed payments forward. The card is cleared in month 10. From month 11 its $100 minimum and the $300 extra join the auto loan’s $300 minimum, so the auto loan receives $700 a month and is paid off in month 25; the student loan then receives the full $900 and is cleared in month 30.
- Run the snowball order. Both strategies clear the card first in month 10, because it is both the smallest balance and the highest rate. After that, snowball targets the student loan, the smaller remaining balance, clearing it in month 23 and the auto loan in month 30.
- Compare total interest. Both plans finish in 30 months. Avalanche pays $2,328.94 of interest and snowball pays $2,441.92, so avalanche costs $112.98 less. Under avalanche, total paid is $26,828.94: the $24,500 of balances plus interest.
How to read your result
The headline is the time until every listed debt is paid under the selected strategy, and the line under it says which strategy pays less interest and by how much. The secondary figures show avalanche interest, snowball interest, both payoff times, and the fixed monthly budget. The chart plots the combined balance under each strategy, so a gap between the lines shows where one plan is ahead.
The schedule table has one row per debt per month, with that debt’s balance, interest, and payment under the selected strategy. The month a debt’s balance first shows $0.00 is its payoff month; the payment on the other debts rises in the next month as its minimum rolls forward.
Each minimum is held at the dollar amount entered. Card issuers usually recalculate minimums as the balance falls, but this planner keeps paying the entered amount, which is what keeps the budget fixed. New purchases, fees, promotional rates, rate changes, and daily interest are not modeled.
What changes the result most
- Total monthly budget
- With the same three debts and only the $600 of minimums, avalanche takes 50 months and $5,115.68 of interest. Adding $100 a month cuts that to 40 months and $3,392.76; $300 to 30 months and $2,328.94; $500 to 24 months and $1,822.67.
- Payoff order
- The order matters less than the budget here. The snowball penalty is $13.43 with no extra, $52.90 with $100 extra, $112.98 with $300 extra, and $120.60 with $500 extra, where snowball also takes 25 months instead of 24.
- Which debts line up
- If the student loan were $18,000 instead of $9,000, the auto loan would be both the smaller and the higher-rate remaining debt after the card, so both strategies follow the same order and cost $3,850.96 of interest over 42 months.
Questions
Which strategy saves more interest?
When rates and minimums are entered accurately, avalanche usually lowers modeled interest because it targets the highest rate first. Snowball may feel more motivating because it removes smaller balances sooner.
Why does the budget stay fixed after a debt is cleared?
The planner assumes you keep paying the same total amount. The minimum that is no longer needed rolls into the next target instead of reducing your monthly debt budget.
Why can my card statement differ?
Many cards calculate interest daily and can add fees or new purchases. This planner uses a monthly approximation and the balances and rates you enter.
How do the debt snowball and debt avalanche methods work?
Both pay every minimum each month and send all extra money to one target debt; when a debt is paid off, its payment rolls to the next target. Avalanche orders targets from the highest interest rate to the lowest. Snowball orders them from the smallest balance to the largest. The monthly total stays the same in both.
What shortens a debt payoff plan the most?
In this model, the size of the monthly budget. In the example, raising the extra amount from $0 to $300 shortens the plan from 50 to 30 months and cuts interest by more than half, while switching between snowball and avalanche changes interest by $112.98. Lower interest rates, for example through a lower-rate loan, also shorten the plan if fees do not offset the saving.
How does a debt consolidation loan change the plan?
A consolidation loan pays off several debts and replaces them with one installment loan at its own rate, term, and fees. Whether it lowers total interest depends on those terms: a lower rate helps, while a longer term or an origination fee can offset it. To compare, enter the consolidation loan here as a single debt and check the result against the current list.
More in Loans & debt
Sources
These references explain the concepts behind the calculation. They do not endorse this site. Estimates leave out any cost or condition you did not enter.