Debt Snowball vs. Avalanche Calculator
Compare the snowball (smallest balance first) and avalanche (highest APR first) strategies for paying off multiple debts.
How to Use
- Enter the balance, APR, and minimum payment for your first debt — this is required.
- Add up to 3 more debts the same way. Leave all three fields of a debt slot blank together to skip it, but if you fill in one of the three, fill in all three.
- Enter any extra amount you can put toward debt every month on top of everyone's minimum payments — leave it at $0 to compare the strategies using minimum payments alone.
- The result shows each strategy's total payoff time and total interest, and which one saves more in this comparison.
Formula
- Every month, every debt
- interest = balance × (APR ÷ 100 ÷ 12); balance += interest; balance −= min(minimum_payment, balance) — any unused portion of a minimum payment (when a debt needs less than the full minimum to finish) joins this same month's pool
- The extra "pool"
- extra_monthly_payment + the minimum payments of any debts already paid off + any unused minimum-payment portion from a debt finishing this month
- Avalanche order
- recomputed every month: the pool goes to whichever open debt currently has the highest APR (ties broken by smaller current balance)
- Snowball order
- recomputed every month: the pool goes to whichever open debt currently has the smallest balance (ties broken by higher APR) — based on the CURRENT balance each month, not the starting balance
Worked Example
A $1,000 balance at 10% APR and a $5,000 balance at 25% APR, each with their own minimum payment, plus $200/month extra to put toward debt.
- Avalanche prioritizes the 25% APR debt first (even though it has the larger balance): payoff in 21 months, $1,304.38 total interest.
- Snowball prioritizes the smaller $1,000 balance first (even though it has the lower APR): payoff in 22 months, $1,452.37 total interest.
- Avalanche saves $147.99 in interest and finishes 1 month sooner in this case.
Result: Avalanche (highest APR first): 21 months, $1,304.38 total interest / Snowball (smallest balance first): 22 months, $1,452.37 total interest / Avalanche saves $147.99 in interest compared to snowball and finishes 1 month sooner.
About This Tool
What this tool does
This calculator simulates paying off multiple debts in parallel two different ways: avalanche, which always directs any extra payment to whichever open debt has the highest interest rate, and snowball, which always directs it to whichever open debt has the smallest balance — while every debt's own minimum payment is preserved every month either way. When a debt is fully paid off, its minimum payment joins the pool of money directed at the next debt in the strategy's order.
When to use it
Use it when you have more than one debt and extra money to put toward paying them down faster, to see the concrete time and interest difference between the two most common payoff strategies before choosing one.
What the result means
Avalanche will always finish with total interest less than or equal to snowball's, because it's mathematically the interest-minimizing order — this calculator quantifies exactly how much that advantage is worth for your specific debts. Snowball's appeal isn't financial: paying off a small balance completely, faster, is a common way to stay motivated when a payoff plan spans many months, even when it costs a bit more in interest.
Assumptions & limitations
This assumes every APR stays fixed for the full payoff period, minimum payments stay the same amount every month, and every dollar of the extra payment pool is applied on time every month with no missed or late payments. It assumes no new charges are added to any balance during the payoff period. This is a projection based on the numbers you enter, not any card issuer's or lender's actual billing calculation, and is not financial or credit counseling advice.