Debt Snowball vs Avalanche Calculator

How to use this tool

1. List every debt. Enter each debt's name, current balance, APR (as a percent), and your current minimum payment. The tool starts with four sample debts; edit or remove them.
2. Set your extra monthly payment. How much above the sum of minimums can you commit each month? Even $50 makes a big dent over time.
3. Read the side-by-side comparison. Snowball results show on the left, Avalanche on the right. Compare months to debt-free, total interest, and payoff order.
4. Check the verdict line. The yellow strip below tells you which strategy wins and by how much. If the gap is small, motivation matters more than pennies.
5. Expand the schedule and export. Open the monthly schedule to see balances each month. Export CSV for tracking, or commit to a strategy and revisit quarterly.

About this tool and how it works

This utility runs 100% in your browser. No data leaves your device. The underlying logic is:

For each month:
  for each debt: interest = balance * (APR/12), balance += interest
  for each debt: pay minimum payment, balance -= minimum
  remaining extra goes to top debt per strategy:
    snowball -> smallest balance first
    avalanche -> highest APR first
  if a debt is paid off, its minimum 'rolls' into the extra payment
  loop until all balances <= 0

You can verify by opening the browser developer tools and watching the Network tab; no requests fire during normal use beyond the initial page and library load.

Real-world scenarios where this tool helps

What this tool does

• Simulates month-by-month debt payoff for any number of debts.
• Accrues monthly interest at APR / 12 on each remaining balance.
• Applies minimum payments to every active debt every month.
• Adds your extra payment plus any rolled-over minimums to the priority debt for each strategy.
• Computes both strategies side by side: Snowball (smallest balance first) and Avalanche (highest APR first).
• Shows total months to debt-free, total interest paid, total amount paid, and full payoff order for each strategy.
• Renders a monthly balance schedule you can expand and export to CSV.
• Updates instantly as you change debts or your extra payment.

What it does NOT do

• Does not handle variable APR. Each debt is treated as a fixed APR for the simulation.
• Does not include compound interest within the month (most credit cards compound daily; the tool uses simple monthly approximation, which is accurate within about 1%).
• Does not account for promotional 0% APR periods that later jump to a higher rate. Use the post-promo APR for safety, or run two simulations.
• Does not deduct cash-back, balance-transfer fees, or annual fees.
• Does not save your data. Refresh and everything resets; use the CSV export to keep a copy.

Common mistakes and pitfalls

• Forgetting that minimum payments rise as balances grow on a credit card. Real card minimums are typically 1-3% of balance, but for simplicity the calculator uses a fixed minimum you enter.
• Using your CURRENT minimum payment without checking the card's rules. If the actual minimum increases, your debt-free date can shift; recompute monthly.
• Adding the same debt twice. Check that you have one row per actual account.
• Picking Snowball purely because Dave Ramsey says so. If the dollar difference is large (over $1,000-$2,000), Avalanche likely wins; pick what gets you to debt-free fastest given your psychology.
• Ignoring the 'rolled minimum' effect. When a debt is paid off, its minimum payment automatically goes toward the next target - that acceleration is included in the math.

Frequently asked questions