Debt payoff calculator: snowball vs avalanche
Enter up to four debts and one number for extra monthly payment. The calculator runs both classic payoff orders - snowball (smallest balance first) and avalanche (highest interest rate first) - and shows the time and total interest for each, so the trade-off stops being abstract.
Which order actually wins?
Mathematically, the avalanche order never loses - money aimed at the highest rate always cancels the most interest. But payoff plans fail for human reasons, not math reasons, and the snowball’s early wins are real fuel. The honest answer: the best method is the one you’ll still be following in month eight.
Related reading
Start with which debt to pay off first for the reasoning in plain English, then the debt snowball method and the debt avalanche method for each system step by step. Weighing a consolidation loan instead? See does debt consolidation always save money.
The formula this calculator uses
every debt receives its minimum each month
the extra payment goes entirely to one target debt
snowball targets the smallest balance first
avalanche targets the highest APR first
when a debt clears, its minimum rolls into the next target
interest each month = balance * APR / 100 / 12
What it assumes without asking
- Minimums stay flat rather than falling with the balance
- No new borrowing on any of the accounts
- APRs hold steady for the whole payoff
- The extra payment is made every month without fail
One example, computed in full: what the order is worth on three debts
| Debt | Balance | APR | Minimum |
|---|---|---|---|
| Card A | $1,200 | 24.99% | $25 |
| Card B | $4,800 | 18.99% | $96 |
| Loan C | $9,000 | 7.50% | $180 |
| Total | $15,000 | mixed | $301 |
What this calculator does not model
- Fees, penalty rates and any promotional period
- The chance that clearing a small balance early keeps you going, which is the actual argument for the snowball and is not a number
- Any change in income during the payoff
The guide behind this tool
A number on its own does not tell you what to do with it. The full month-by-month simulation of these exact debts, and what the two orders cost against each other, is in debt snowball against debt avalanche.
Sources & further reading
This tool is general education, not personalized financial advice. It assumes fixed rates and payments and ignores fees - real accounts vary. See our disclaimer.