Debt Payoff Calculator (Snowball vs Avalanche)
Simulate accelerated payoff timelines and discover how much compounding interest you can eliminate.
What is the difference between Debt Snowball and Debt Avalanche?
Debt Avalanche pays off balances with the highest interest rates (APR) first, mathematically minimizing total interest costs. Debt Snowball prioritizes the smallest loan balances first to provide rapid psychological momentum.
Outstanding Debt Accounts (3)
| Account | Balance | Interest (APR) | Min Payment | |
|---|---|---|---|---|
| Chase Sapphire Preferred | $4,500.00 | 24.99% | $150.00/mo | |
| Auto Loan (Honda Civic) | $9,200.00 | 5.49% | $260.00/mo | |
| Graduate Student Loan | $14,800.00 | 6.8% | $210.00/mo |
Add Liability
How This Calculator Works
SphereBudget's interactive debt payoff calculator deterministically simulates amortization schedules across multiple loans and revolving accounts. By comparing the behavioral Debt Snowball against the mathematically optimal Debt Avalanche, the engine calculates exact interest charges, payoff dates, and the compounding velocity of rolled-over monthly minimum payments without transmitting your data.
Inventory Contractual Minimums
Enter your principal balances, nominal annual percentage rates (APR), and mandatory minimum payments. The engine establishes a baseline floor required to prevent lender delinquency penalties.
Select Strategy: Snowball vs. Avalanche
Choose Debt Avalanche to mathematically minimize total finance charges by attacking the highest APR first, or Debt Snowball to clear the smallest balance first for behavioral momentum.
Simulate the Cascading Rollover
When an account hits $0, its minimum payment automatically rolls into your active extra payment pool, creating an accelerating repayment wave that crushes subsequent balances in record time.
Worked Example Scenario: $15,000 Total Debt Portfolio
Consider a realistic scenario with 3 distinct accounts totaling $15,000 in balance:
Account 1: Credit Card A ($3,000 balance at 22.99% APR, $90 min) • Account 2: Credit Card B ($5,000 balance at 17.99% APR, $120 min) • Account 3: Consolidation Loan ($7,000 balance at 8.99% APR, $160 min).
| Payoff Strategy | Monthly Commitment | Payoff Timeline | Total Interest Paid | Total Money Saved | Time Saved |
|---|---|---|---|---|---|
| Minimums Only (No Extra) | $370 / mo | 88 Months (7.3 yrs) | $7,420 | $0 | Baseline |
| Debt Snowball ($200 Extra) | $570 / mo | 33 Months (2.75 yrs) | $3,682 | +$3,738 Saved | 55 Mos Faster |
| Debt Avalanche ($200 Extra) | $570 / mo | 31 Months (2.6 yrs) | $3,312 | +$4,108 Saved | 57 Mos Faster |
Methodology & Assumptions
- Periodic Compounding Frequency (monthlyRate = APR / 12)
- Calculations assume 12 uniform monthly compounding periods per year with periodic rate
monthlyRate = APR / 12(decimal:i = (APR / 100) / 12). While revolving credit card issuers may calculate daily finance charges using an Average Daily Balance (ADB), the monthly discrete model provides a consistent benchmark within fractions of a percent. - Strategy Sorting Algorithms
- Priority sorting rules applied to target liabilities:
- • Avalanche:
debts.sort((a, b) => b.apr - a.apr)(mathematically minimizes total interest) - • Snowball:
debts.sort((a, b) => a.balance - b.balance)(maximizes early psychological wins)
- • Avalanche:
- Constant Rate Stability
- Annual Percentage Rates (APRs) are modeled as static throughout the duration of the loan term. Variable index changes (e.g. Federal Reserve benchmark rate changes) or promotional balance transfer expiration windows are not factored in automatically.
- Contractual Minimum Floor
- The simulation assumes timely, uninterrupted minimum payments across all active accounts every cycle. No late fees, over-limit penalties, or punitive default interest rates are triggered during the projected amortization lifecycle.
- Cascading Extra Payment Multiplier
- When a debt balance reaches $0, the entirety of its contractual minimum payment is automatically redirected to the next priority loan (ordered by
b.apr - a.aprfor Avalanche ora.balance - b.balancefor Snowball), accelerating principal reduction.
Everything You Need to Know About Debt Elimination
Which method is objectively better: Debt Snowball or Debt Avalanche?
How does the calculator handle monthly interest compounding?
i = (APR / 100) / 12. Each month, your payment is first allocated to cover the accrued monthly interest charge, and the entire remaining balance of your payment reduces the principal balance directly. Full formula details are available on our Methodology page.