Credit Card Payoff Calculator — Avalanche or Snowball
Enter your cards and one monthly budget to see when you will be debt-free, what interest costs, and what avalanche or snowball saves versus minimums.
A clear path from inputs to results.
Line up every card and loan, set one monthly budget, and see exactly when you will be debt-free under the avalanche (highest APR first) or snowball (smallest balance first) method. The tool simulates each month — interest, minimums, then surplus to your priority order — and compares the result with paying minimums only.
How to use
- Add each debt with its name, balance, APR and minimum payment; the three starter cards can be edited or removed.
- Set the total monthly budget you can commit; the engine never lets it fall below the sum of your minimum payments.
- Choose avalanche (highest APR first, cheapest in interest) or snowball (smallest balance first, quickest visible wins).
- Optionally enter expected late payments per year; the model adds the CFPB-capped $8 fee, spread across the months and active cards.
- Read the results: months to debt-free and the payoff date, total interest, the weighted-APR gauge, and the interest saved versus minimum-only payments.
- Open the ledger for the month-by-month balances, interest and payments.
The formula
Reference: Revolving-credit amortisation with monthly interest = balance × APR ÷ 12, minimums paid first, simulated month by month (Broverman, Mathematics of Investment and Credit).
Worked example
Three debts, $1,000 a month, avalanche
- Card A: $5,000 at 24.99% (minimum $150); card B: $3,000 at 18.99% (minimum $90); loan: $10,000 at 9.5% (minimum $200); total minimums $440; budget $1,000 a month; avalanche order; no late fees expected.
- 1
The balances total $18,000 with a weighted APR of 15.38%. Each month the engine accrues interest at APR ÷ 12 on every balance, pays all minimums ($440 combined), then sends the remaining $560 to the highest-APR debt (the 24.99% card) until it is gone, then the next. After 21 months every balance reaches zero and cumulative interest is $2,073.20. Paying only the $440 minimums instead drags on for years and accrues about $7,600 (the tool caps its baseline run at 600 months), so the extra $560 a month saves about $5,627.36 by the tool's own comparison.
Debt-free in 21 months (about one year and nine months); total interest $2,073.20; roughly $5,627 saved versus minimum-only payments.
Interpreting the result
The weighted-APR gauge shows the average rate your combined balances carry — the interest figure is what that rate costs over the whole payoff. The savings number answers the practical question of what your budget above the minimums is worth. If the payoff date feels too far out, raise the budget and watch months and interest fall together; the ledger shows exactly when each debt disappears, which the snowball method makes visible sooner by design.
Assumptions & limitations
- APRs and minimum payments stay fixed for the whole simulation; no balance transfers, promotional rates or new charges on the cards.
- The engine uses an effective budget of max(your budget, sum of minimums), so a budget below the minimums is automatically topped up.
- Expected late payments are charged at the CFPB maximum late fee ($8) per incident, spread evenly across the year and the active cards.
- Interest is computed monthly (APR ÷ 12) with no grace periods; the simulation caps at 600 months (50 years).
- Payoff dates are projected from the current month, so actual dates shift if payments start later.
Frequently asked questions
Avalanche or snowball — which is cheaper here?
On the example stack both take 21 months, but avalanche costs $2,073.20 in interest versus $2,186.63 for snowball — about $113 less — because it always attacks the highest rate first. Snowball clears the $3,000 card first, which feels faster even though the end date is identical. The math favors avalanche; the better method is the one you will actually stick to.
How much does a bigger budget help?
Steeply. Raising the example budget from $700 to $1,000 a month cuts the payoff from 31 months to 21 and interest from $3,254.38 to $2,073.20 — $1,181.18 saved for $300 more per month. The first extra dollars go to your highest-rate balance, where they stop the most interest.
Why does the weighted APR matter?
It is the balance-weighted average of your rates — 15.38% on the example — and it approximates what your debt costs while all balances are outstanding. It falls as high-rate debts are retired first, which is why the avalanche method targets the most expensive balances before anything else.
What happens if I pay only the minimums?
Minimums are designed to keep you in debt a long time: at exactly $440 a month the example debts take about 59 months and roughly $7,600 of interest to clear. The tool's built-in baseline comparison caps its minimum-only run at 600 months, which is why the savings figure it reports can be larger than a shorter simulation would show.
What does the late-payment input do?
If you expect, say, two late payments a year, the model adds the regulatory maximum late fee of $8 per incident, spread across the months and the active cards. It is a small drag per month here, but repeated late fees often trigger penalty APRs in real life, which this fixed-rate model does not capture.
Does the tool assume I stop using the cards?
Yes. Balances only grow by interest (and any expected late fees) and shrink by payments; there is no mechanism for new spending. New charges would raise the balances and push every date and dollar shown in the wrong direction.
Methodology last reviewed 2026-10-06. Results are informational and not financial or engineering advice — see our disclaimer.