NumberTally Debt Payoff Calculator
List every debt, add one extra monthly payment, and compare the snowball vs avalanche payoff strategies side by side — payoff date, total interest, and a month-by-month balance chart for each.
Your debts
On top of all minimums. Paid toward the target debt first, then rolled to the next one.
Snowball vs avalanche: psychology vs math
The avalanche method attacks the highest interest rate first. Because every dollar of extra payment kills the most expensive interest first, it always minimizes total interest — the math is unambiguous. The snowball method attacks the smallest balance first, so you get a "paid in full" win sooner. Studies on debt behavior find that early wins keep people motivated, and a plan you stick with beats a perfect plan you abandon.
In practice the gap is often smaller than people expect. When your highest-rate debt is also fairly small, both methods pick the same target and the results are nearly identical. Run your own numbers above — the verdict box shows exactly what each strategy costs you.
Why minimum payments keep you in debt for decades
A typical credit card minimum is around 2% of the balance. On a $5,000 balance at 20% APR, the minimum starts near $100 — but $83 of that is interest. You chip barely $17 off the principal. As the balance shrinks, so does the minimum, which stretches the payoff over decades and multiplies the interest. The chart above makes this visible: watch how slowly the balance falls when only minimums are paid versus how the extra payment bends the curve down.
Frequently Asked Questions
Which is better, snowball or avalanche?
Avalanche always pays less total interest. Snowball pays off the first debt sooner, which helps motivation. If the interest gap between your debts is large, avalanche wins by a lot; if rates are similar, pick whichever keeps you going.
What happens to a minimum payment when its debt is paid off?
It rolls over. Your total monthly payment stays the same the whole time — every freed-up minimum plus your extra payment attacks the next target debt. That rollover is what makes the payoff accelerate.
What if my minimum payment doesn’t cover the interest?
Then the balance grows forever and the debt never pays off — the calculator will tell you. You need to pay more than the monthly interest charge (balance × APR ÷ 12) for the balance to fall.
Should I include my mortgage?
Usually not in the same plan. Mortgages have much lower rates and are secured by the house; most payoff strategies target unsecured high-rate debt first. List credit cards, personal loans, auto loans, and student loans here.
How is the payoff date calculated?
Month by month: interest accrues on each balance, minimums are paid on every debt, and whatever is left of your total budget goes to the target debt. The payoff date is today plus the number of simulated months.