Debt Payoff Calculator (Snowball vs. Avalanche)
List your debts, add an extra monthly payment, and compare the snowball and avalanche methods — months to debt-free, total interest, and your exact payoff order.
On top of all minimums — even $50 changes the math
Payoff strategy
Debt-free in
2 years 5 months
Total interest paid
$2,006
vs. snowball
Same interest
Your payoff order (avalanche)
- 1Credit cardpaid off in 1 year 4 months
- 2Car loanpaid off in 2 years 5 months
How the simulation works
Each simulated month, interest accrues on every balance at its APR (1/12 per month), minimum payments land on every debt, and your extra payment — plus any minimums freed by paid-off debts — attacks the target: smallest balance first (snowball) or highest APR first (avalanche). This "rollover" effect is why payoff accelerates near the end: the last debt gets hit with everything at once.
The calculator runs both strategies on your numbers simultaneously and shows the difference, so the snowball-vs-avalanche debate stops being abstract. For the full argument — including when the "wrong" method is the right choice — read our snowball vs. avalanche guide.
Finding the extra payment
The single biggest input is the extra monthly amount, and it usually hides in the "wants" bucket of your budget. If you don't have a budget yet, the 50/30/20 calculator takes one minute — the 20% savings bucket is exactly where extra debt payments live. A canceled subscription here and a negotiated bill there routinely finds $100–$300 a month, which this calculator will translate into years of your life back.
Keep one hand on the safety rail
Aggressive payoff with zero savings is fragile — one car repair lands right back on the credit card. Most planners suggest a $1,000–$2,000 starter emergency fund before going all-in on debt, then building the full 3–6 month fund after the high-APR balances are gone. As balances fall, watch the effect on your net worth — payoff is invisible in your checking account but very visible there.
Frequently asked questions
What's the difference between debt snowball and debt avalanche?
Both pay minimums on everything and aim extra money at one target debt. Snowball targets the smallest balance first for quick psychological wins; avalanche targets the highest APR first, which is mathematically optimal — it always costs the least total interest. When a debt dies, its payment rolls into the next target.
Which method should I choose?
Avalanche if the numbers motivate you — it saves the most money. Snowball if crossed-off debts motivate you — behavioral research (including a well-known HBR/Kellogg analysis) suggests people who see early wins are likelier to finish. The best method is the one you'll actually sustain; the calculator shows you the exact price difference between them.
Should I pay off debt or invest first?
The common rule of thumb: debt above ~7% APR (credit cards at 20%+ especially) beats what markets reliably return, so attack it first. Below ~4–5% (many mortgages, some auto loans), investing alongside minimum payments is usually reasonable. In between is judgment and risk tolerance — and always take an employer 401(k) match first; it's an instant 50–100% return.
Why does the calculator say my balances never reach zero?
If a debt's minimum payment is smaller than its monthly interest charge, the balance grows every month no matter how long you wait. You'll need to raise the payment on that debt — or the extra monthly amount — for any payoff plan to work.
Do extra payments really matter that much?
Enormously, because every extra dollar goes straight at principal. On a $4,500 credit card at 25% APR with a $135 minimum, adding just $200/month typically turns a decade of payments into under two years and saves thousands in interest. Run your own numbers above.
Is this calculator private?
Yes — every number stays in your browser. Nothing is uploaded, stored, or tracked.
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