Add your debts — cards, loans, bills — plus an extra monthly payment to compare what the avalanche and snowball strategies actually cost in interest.
How to Use the Debt Payoff Calculator
List each debt — credit cards, a car loan, a personal loan, medical bills, anything with a balance, a rate, and a minimum payment — then set an extra amount you can put toward debt beyond those minimums each month. The calculator simulates two payoff strategies against the exact same numbers.
The two approaches disagree about what "priority" means. Avalanche ranks debts by APR — highest rate first — because interest rate determines how fast a balance grows if it's left alone; a 22% card is doing more damage per dollar owed than a 6% car loan, no matter which one is bigger. Snowball ranks by balance instead — smallest first — on the theory that clearing a whole debt outright, even a cheap one, produces a psychological win a partial dent in a bigger balance doesn't.
- Avalanche priority: highest APR first
- Snowball priority: smallest balance first
Every month, both strategies pay each debt's minimum in full, then throw whatever's left — the extra amount plus the freed-up minimums from any already-paid-off debts — at whichever debt is next in priority order. That "freed-up minimum" detail matters: total monthly outlay never grows over the course of the payoff, it just gets redirected as debts clear.
Because avalanche always attacks the debt costing the most per dollar, it mathematically can't produce more total interest than snowball on the same set of debts — at worst they tie. What snowball buys instead is speed to a first win: on the numbers filled in by default here, snowball clears the personal loan by month 8, while avalanche doesn't clear its first target, the credit card, until month 12 — a real head start, and the whole appeal for anyone who's abandoned a payoff plan before out of sheer fatigue.
Neither strategy accounts for a 0% promotional balance-transfer offer, a consolidation loan, or a hardship withdrawal — all of which change the math in ways this simulator, built strictly around minimum-payment-plus-extra behavior, doesn't try to capture.