The Debt Snowball Calculator builds your month-by-month payoff plan using the debt snowball method: minimum payments on everything, and every spare dollar aimed at your smallest balance until it disappears, then rolled into the next. Enter each debt's balance, interest rate, and minimum payment, plus the total monthly amount you can pay across all debts.
How It Works
Debts are sorted from smallest balance to largest. Each simulated month, interest accrues on every balance at its monthly rate, minimums are paid on all debts, and the extra budget (your monthly budget minus the total of all minimums) goes entirely to the smallest remaining debt. When a debt clears, its minimum payment joins the extra, so the attack amount snowballs. The plan reports total months to debt-free, total interest, the payoff order, and the month and interest cost of each individual debt.
Parameters
| Input | Required | Meaning | |---|---|---| | Each debt's balance | Yes | Current amount owed | | Each debt's APR | Yes | Annual interest rate for that debt, 0 to 100 | | Each debt's minimum payment | Yes | Required monthly minimum | | Monthly budget | Yes | Total you can pay monthly; must cover all minimums |
Worked example
Three debts: a 25), a 60), and a 110). Minimums total 400 budget leaves a 20.88), the freed 230, the credit card clears in month 12 (595.07). Total interest for the plan is 8,911.65 in total on $8,000 of debt.
Snowball versus avalanche
The avalanche method aims extra money at the highest APR instead, and on identical numbers it never costs more interest than the snowball, usually less. The snowball's counter-argument is behavioural: closing an account in month 3 delivers a win while motivation is fragile, and a plan abandoned in month 5 costs more than either method completed. Choose avalanche if you are confident you will stick to the plan regardless; choose snowball if quick account closures are what will keep you going. This calculator models the snowball; its sibling debt avalanche calculator models the other order so you can compare the interest difference on your real numbers before deciding.
Making the plan faster
Every extra dollar of monthly budget shortens the plan and cuts interest, and it counts most early, when balances are largest. Selling something to delete the smallest debt instantly starts the snowball one step ahead. Conversely, adding new charges to a card in the plan silently breaks the simulation, because the model assumes balances only fall.
Limitations
The simulation assumes fixed APRs, fixed minimums, and no fees, penalties, or new spending. Real credit-card minimums usually shrink as the balance falls (the model conservatively holds them at the figure you enter once payments start rolling, following the plan's roll-forward logic), and promotional rates expire. Re-run the plan whenever a rate or balance changes materially.
The minimum-payment trap the plan avoids
Left on minimums alone, small balances linger for years because card minimums are often set near the interest charge itself. On the 25 minimum without the snowball would still clear it, but the 60 minimum would crawl, and any month where a minimum dips below the month's interest the balance grows despite payment. The snowball structure protects against this by guaranteeing the current target debt receives the minimum plus the entire freed surplus, so exactly one balance is always in rapid decline and the rest are serviced properly.
What to do with a windfall
A tax refund, bonus, or sold item raises the classic question: throw it at the current target debt, or split it? Inside the snowball logic, the answer is mechanical: pay the current smallest balance down first, because deleting a whole debt early frees its minimum a month sooner and accelerates every later step. The exception is a windfall large enough to clear two debts when one carries a much higher rate: run the calculator with the balances reduced each way and choose the plan with the lower total interest if the months-to-free outcome is close. Emotion built the snowball, but arithmetic is allowed to overrule it when the numbers are not close.
Frequently Asked Questions
How much extra does the snowball cost versus the avalanche?
It depends on how different your rates and balances are. When the smallest debt also carries a high rate, the two methods nearly coincide. Run both calculators on your debts; if the difference is small, take the method you will actually finish.
What if my budget only just covers the minimums?
Then the initial snowball is zero and the smallest debt still clears first, just slowly, because its minimum is proportionally larger. Any amount you can add, even $25, starts the roll noticeably earlier.
Should I include my mortgage or car loan?
You can, but most people sequence consumer debts first because their rates are higher and balances smaller. Secured debts also carry repossession or foreclosure stakes that a pure balance ordering does not capture.