Debt Snowball / Avalanche Calculator
Compare snowball and avalanche strategies to pay off your debt faster. Add your debts, set an extra payment amount, and see your debt-free date, total interest paid, and month-by-month payoff plan.
Pays highest interest rate first — saves the most money.
How This Calculator Works
This calculator runs a month-by-month simulation of your actual debts. Each month, every debt accrues one month of interest, minimum payments go out to all of them, and then your extra payment attacks a single target: the smallest balance (snowball) or the highest interest rate (avalanche). When a debt is wiped out, its minimum payment rolls into the attack pool — that’s the snowball getting bigger as it rolls.
Monthly interest = current balance × (APR ÷ 12)The simulation repeats this for every debt, every month, until all balances hit zero. Your debt-free date and total interest paid come straight from that schedule — no shortcuts or approximations.
Assumptions baked into the math
- Interest accrues monthly on the current balance of each debt.
- Minimum payments stay fixed at the amounts you enter (card issuers often lower minimums as balances shrink — paying a fixed amount is faster).
- Your extra payment stays the same every month.
- No new charges get added to the debts along the way.
A worked example
Say you have a $3,000 loan at 6% ($100 minimum) and a $9,000 credit card at 22% ($225 minimum), with $200 extra each month. Snowball (loan first) makes you debt-free in 35 months with $3,773 in total interest. Avalanche (card first) takes 29 months and $2,748 — about $1,025 and half a year saved. On paper, avalanche always wins. In real life, the winner is whichever one you actually stick with.
Frequently Asked Questions
What is the debt snowball method?
The debt snowball method pays off debts from smallest balance to largest, regardless of interest rate. Once the smallest debt is paid off, you roll that payment into the next smallest. The psychological wins from eliminating debts quickly help keep you motivated.
What is the debt avalanche method?
The debt avalanche method targets the debt with the highest interest rate first, regardless of balance. This approach saves you the most money in total interest paid, but it may take longer to eliminate your first debt.
Which method saves more money?
The avalanche method will always save you more in total interest because it prioritizes expensive debt first. However, the snowball method can be more effective for people who need quick wins to stay motivated. The best method is the one you stick with.
How much extra should I pay toward debt each month?
Even an extra $50-$200 per month can dramatically shorten your payoff timeline and save thousands in interest. Use this calculator to see the impact of different extra payment amounts on your specific debts.
Should I invest or pay off debt first?
A common rule of thumb: pay off any debt with an interest rate above 6-7% before investing (since the stock market averages about 7% after inflation). For lower-rate debt like mortgages, you may benefit from investing while making minimum payments.