❄️ Debt Snowball Calculator
Pay off multiple debts using the snowball or avalanche method. See your debt-free date, total interest, and which strategy saves more.
| Debt Name | Month Cleared |
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| Month | Total Balance |
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How to use this calculator
Takes about 4 minutes.
- Add each debt with its balance, APR, and minimum payment
- Click 'Add another debt' until all debts are listed
- Enter how much extra you can pay each month
- Choose snowball (smallest balance first) or avalanche (highest APR first)
- Review your debt-free date, payoff order, and total interest
Try these scenarios
Tap a scenario to load it into the calculator above.
Methodology
The calculator runs a month-by-month amortisation across all debts. For each month it: (1) accrues interest on each balance at APR ÷ 12, (2) applies the minimum payment to every debt, then (3) directs your extra monthly payment plus any freed-up minimums (the "snowball") at the focus debt. The focus debt is the smallest remaining balance under snowball, or the highest APR under avalanche. When a debt is cleared, its minimum is rolled into next month's snowball — which is why the last few debts disappear so quickly.
The snowball strategy is most associated with Dave Ramsey's The Total Money Makeover (2003), which popularised the smallest-balance-first approach for its behavioural momentum. Avalanche is the mathematically optimal interest-minimising order. This is a pure-math calculator with no external data sources — the only inputs are the ones you enter above.
Last verified: May 2026.
Key concepts
Snowball vs. avalanche. The snowball pays smallest balances first for psychological wins. The avalanche pays highest-APR debts first for the lowest total interest. Avalanche always wins on maths; snowball often wins on follow-through. Dave Ramsey popularised snowball precisely because behavioural research shows quick wins build momentum.
How extra payments compound. When you clear one debt, its former minimum payment rolls onto the next debt. Each clearance accelerates the rest — the snowball gets bigger as it rolls. This is why even a modest extra payment can cut years off a payoff timeline.
Always pay all minimums. Neither strategy works if you miss minimums — late fees, rate hikes, and credit-score damage compound faster than any principal reduction. Extra goes to the target debt; everything else stays on schedule.
When the gap is huge. If your highest-APR debt is dramatically more expensive (say 24% credit card vs. 5% car loan), avalanche can save thousands. If APRs are similar, snowball's behavioural advantage usually wins. Personal-finance researchers including Northwestern's Kellogg School have found snowball completers outperform avalanche planners in long-run debt elimination.
Stop the bleeding first. Neither strategy works if you keep adding to balances. Build a small emergency cushion ($500-$1,000) so unexpected expenses don't go on the card you're trying to pay down — then attack the debts in earnest.
Frequently Asked Questions
Worked example
Thandi in Johannesburg has three debts: a R12,000 store card at 22% APR with a R400 minimum, a R45,000 personal loan at 15% with a R1,100 minimum, and a R8,000 credit card at 18% with a R250 minimum. She can put R1,500 extra a month on top of her R1,750 in combined minimums.
Under snowball (smallest balance first), the R8,000 credit card clears in about five months. Its freed-up R250 then rolls onto the R12,000 store card, which clears around month 12. The full R1,900 then attacks the R45,000 loan, which clears around month 33. Total interest paid: roughly R11,500 over 33 months.
Under avalanche (highest APR first), she attacks the 22% store card first, then the 18% credit card, then the 15% loan. Total interest: roughly R10,800, debt-free at month 33. The behavioural lever: snowball delivers two cleared debts inside a year, which keeps most people committed. Avalanche saves R700 over three years — real, but small enough that the strategy you actually finish wins.
Common mistakes
- Adding new debt during payoff. The most common failure mode: freed-up cash from a cleared card silently funds a car upgrade, a holiday or a new store card, restarting the cycle. Automate the freed minimums into the next debt before they hit your current account.
- Including the wrong debts. Mortgages, UK income-contingent student loans and 0% promo balances do not belong in the snowball with credit cards. Mortgages are low-rate and tax-treated; UK student loans behave like a graduate tax; 0% balances need to be cleared by promo expiry, not by APR ranking.
- Skipping minimums on non-focus debts. Missing any minimum triggers late fees, possible rate hikes to 29.99% penalty APR, and a 30-90 day credit-score hit that costs more than any principal saved. Extra goes to the focus debt; everything else stays on autopay.
- No emergency cushion. Throwing every spare rand or dollar at debt without a R10,000 / $1,000 buffer means the next car repair or vet bill goes straight back on the card you just cleared. Build a small cushion first, then attack.
- Picking snowball when the gap is huge. If your top APR is 24% and your smallest balance is on a 6% car loan, avalanche can save thousands. Use the calculator to see your specific interest gap — if it is more than 10-15% of the total payoff cost, switch.
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