Debt Snowball vs Avalanche Calculator

Snowball vs avalanche: how each method actually works

Both methods run on the same engine. Keep paying the minimum on every debt, then throw every extra dollar at one target debt until it's gone. When that debt hits zero, roll its entire payment into the next target. Repeat until you're done. The only thing that changes is the order you attack them in, and that order matters more than you'd think.

Debt snowball (smallest balance first). List your debts from smallest balance to largest and ignore the interest rates completely. Attack the smallest one first with every spare dollar while paying minimums on everything else. When it's gone, its payment rolls onto the next-smallest debt. The snowball grows with every debt you clear. It's not about the maths, it's about momentum: wiping out a whole account in a few months feels genuinely good, and that feeling is what keeps most people going.

Debt avalanche (highest rate first). Flip the order. List your debts from highest interest rate to lowest and attack the most expensive one first, regardless of its balance. This is always at least as good mathematically, and usually better, because you're cutting off interest at the source. Every dollar you put toward a 20% credit card saves more than the same dollar put toward an 8% car loan.

Read the full breakdown, including how each order plays out debt by debt, in our debt snowball vs avalanche guide.

Worked example: three realistic Australian debts

Here's a scenario that'll feel familiar. A credit card at $8,000 (20% APR, $160 minimum), a car loan at $15,000 (8% APR, $300 minimum), and a personal loan at $6,000 (12% APR, $150 minimum). Minimums total $610/month. With $200/month extra to throw at debt, the total monthly budget is $810.

Under snowball, the $200 extra goes to the personal loan first, since it has the smallest balance. With $350/month hitting it, it clears in roughly 18 months. That frees up $350 to roll onto the credit card, which clears around month 30, and the full $810 then knocks out the car loan by month 38. Under avalanche, the $200 extra goes to the credit card first, since it's costing the most. With $360/month hitting it, it clears in roughly 26 months, then the personal loan goes fast, and the car loan wraps up around month 36. Avalanche wins by around $600 and two months, not a fortune here, but the gap widens fast with bigger balances or wider rate spreads. Enter your own numbers above to see your version of this trade-off.

The psychology behind the snowball method

Here's what the pure-maths crowd tends to miss: most people who start a debt repayment plan don't finish it. In 2012, researchers Dr David Gal and Blakeley McShane published a study in the Journal of Marketing Research, using data from thousands of real debt management clients, and found that account elimination, not the dollar amount paid off, was the strongest predictor of whether someone actually cleared all their debt. People who knocked out whole accounts, even small ones, were far more likely to finish than people chipping away at large balances without ever seeing a zero.

Behavioural economists call this the small wins effect: each paid-off account triggers a little hit of motivation that reinforces the behaviour, so you keep going. ASIC's MoneySmart acknowledges this too, describing the snowball approach as a way to help you stay motivated as you clear each debt, a rare nod to psychology over pure maths from a government regulator. If you've tried to pay off debt before and lost steam around month four, the snowball isn't the dumb choice. It might be the smart one.

The hybrid approach: best of both worlds

You don't have to pick a lane and stay there forever. Start with one quick snowball win, clearing your smallest debt first to build confidence and free up some cash flow, then switch to avalanche order for everything left. You get the motivational boost of an early win and the mathematical efficiency of attacking your most expensive debt sooner. It's not theoretically optimal, but it's practically excellent, because it keeps you in the game.

If your debts are spread across several high-rate products, it's also worth weighing up debt consolidation, rolling everything into one lower-rate loan can beat both snowball and avalanche on total interest paid. The catch is it only works if you don't run the cards back up once they're cleared.

Common mistakes to avoid

• Only paying minimums. On an $8,000 credit card at 20% APR, minimums alone take over 7 years and cost more than $5,500 in interest. Even an extra $50/month changes that dramatically.
• Prioritising HECS-HELP over high-interest consumer debt. HECS-HELP is indexed to CPI, not charged compound interest like a credit card. Clear the expensive stuff first and revisit your HECS balance after.
• Skipping a small emergency fund first. Going all-in on debt without a buffer means one car repair puts you straight back on the credit card. A $1,000-$2,000 starter fund is insurance for your plan, not a detour from it.
• Cancelling credit cards too quickly. Closing an account you've just cleared reduces your available credit limit, which can push up your credit utilisation and dent your credit score in the short term. If you don't trust yourself with it, cut it up but consider leaving the account open for a while.
• Forgetting BNPL debts like Afterpay and Zip. They don't always show up on credit reports, but they're real debts with real consequences. Add every BNPL balance to the calculator above alongside your other debts.
• Not automating extra repayments. Willpower runs out. If your extra payment relies on you manually transferring money each month, it'll get skipped when life gets busy. Automate it on payday instead.