List your debts and a monthly budget to see your debt-free date and total interest with the snowball method, plus a side-by-side comparison against the avalanche method.
This must cover every minimum payment; whatever is left becomes the snowball.
Snowball — smallest balance first
Avalanche — highest APR first
| # | Debt | Starting balance | Cleared in month | Interest it cost |
|---|
Debts are listed in the order the snowball clears them — smallest balance first. "Cleared in month" counts from the first month of the plan.
Each line is the combined balance of all debts. A steeper, shorter line means the debt is gone sooner; the gap between the lines shows how the two strategies diverge.
For beginners: how to read this result
To get a result, load one of the example debt sets or build your own list: for each debt enter a name, the balance owed, its APR and the minimum monthly payment. Then enter the total amount you can put toward debt every month. The calculator runs a month-by-month simulation and shows your debt-free date straight away.
How the debt snowball works
The snowball method is a fixed monthly routine. Every month the calculator does three things for every open debt. First it adds one month of interest: interest equals balance times APR divided by 1200 (the APR is annual, so it is split across 12 months). Next it pays the minimum payment on every debt. Finally it takes whatever is left of your budget after all the minimums — the “snowball” — and sends the entire amount to a single debt: the one with the smallest current balance.
The key effect is the roll-over. When a debt reaches zero, its minimum payment is no longer needed, so that money is freed up and joins the snowball for the remaining debts. Each cleared debt makes the snowball bigger, so the later debts fall faster and faster. That is why the method is named after a snowball rolling downhill.
Reading the result
The headline tells you in how many months — and how many years and months — every debt is cleared, along with the total interest you will pay along the way. The payoff order table lists each debt in the sequence the snowball clears it, with the exact month it disappears and the interest it cost. The total amount paid is principal plus all interest.
Snowball versus avalanche
The same engine also runs the avalanche method, where the spare snowball goes to the debt with the highest APR instead of the smallest balance. Avalanche always pays the least total interest because it removes the most expensive rate first. Snowball usually clears the first debt sooner, which gives a visible early win that many people find easier to stick with. The comparison block shows months and interest for both so you can see the trade-off and choose: avalanche to pay less, snowball to feel faster progress. The chart draws the total remaining debt for both methods declining to zero.
Budget check and limits
Your monthly budget must be at least the sum of every minimum payment, otherwise the debts cannot all be serviced and the calculator shows a warning instead of a plan. The projection assumes balances, APRs, minimum payments and your budget all stay constant until the debt is gone, and it is capped at a 100-year horizon. It does not model fees, late penalties, promotional zero-percent periods, balance-transfer costs, changes in income or any effect on a credit score. Treat the figures as a planning estimate and confirm exact terms with each lender.