Wealth & retirement · super (composes 3 primitives)
Debt avalanche vs snowball
Type your debts. We simulate avalanche (target highest APR first) and snowball (target smallest balance first) month-by-month, surface total interest paid + months to zero for both, and surface the tradeoff: avalanche always wins on dollars, snowball usually wins on motivation.
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Inputs
Result
Avalanche saves $0 of interest over snowball — 63 mo vs 63 mo to debt-free.
No meaningful difference: Avalanche and snowball converge on this debt mix. Pick the one you'll actually do.
- 1
Total debt balance
$46,500
3 debts combined
- 2
Avalanche (highest APR first)
63 months · $7,841 interest
Order: Credit card → Auto loan → Student loan
- 3
Snowball (smallest balance first)
63 months · $7,841 interest
Order: Credit card → Auto loan → Student loan
- 4
Avalanche savings
$0
0 months faster too
- 5
First debt eliminated (avalanche)
Credit card
Highest-APR debt is the math-optimal target
- 6
First debt eliminated (snowball)
Credit card
Smallest balance gets eliminated fastest — psychology win, even if costs more
Assumptions & notes
- Simulation runs 63-month month-by-month with min payments + extra applied to the target debt. Interest accrues monthly on each debt's balance.
- Avalanche maximizes math; snowball maximizes momentum. Real-world data from Northwestern and HBR shows snowball followers stick with plans longer.
- Refinance / consolidation can change the answer — check whether a 0% balance transfer or personal loan beats either strategy.
Multi-scenario comparison
What if — ±20% on one input
| Scenario | Debt 1 balance | Headline | Δ vs baseline | Magnitude |
|---|---|---|---|---|
| −20% (cautious) | $6,800 | Avalanche saves $0 of interest over snowball — 61 mo vs 61 mo to debt-free. | $-1,700 | |
| Baseline | $8,500 | Avalanche saves $0 of interest over snowball — 63 mo vs 63 mo to debt-free. | 0 | |
| +20% (aggressive) | $10,200 | Avalanche saves $0 of interest over snowball — 65 mo vs 65 mo to debt-free. | +$1,700 |
Try the input with the highest sensitivity (above). The Δ column shows the dollar swing from a 20% move — that's how much room you have for a counter, raise, or hedge.
Goal seek
Solve for an input value
Pick the input you want to vary and the output you care about. We'll find the input value that gets you to the target. Bisection-based; converges in < 50 iterations.
Monte Carlo simulation
Distribution under input uncertainty (500 trials)
We perturb every numeric input with normal-distributed noise (10–25% sigma depending on input type) and run 500 compute trials. The output is a probability distribution, not a single number — closer to how finance actually works.
Most-leveraged inputs (sensitivity analysis)
Where to focus — what moves the answer most
Each input perturbed ±10%; measured impact on Total debt balance. Higher elasticity = bigger lever.
- 1
Debt 3 balance
Elasticity ↑ 0.47× — 10% change in this input increases Total debt balance by 4.7%.
- 2
Debt 2 balance
Elasticity ↑ 0.34× — 10% change in this input increases Total debt balance by 3.4%.
- 3
Debt 1 balance
Elasticity ↑ 0.18× — 10% change in this input increases Total debt balance by 1.8%.
- 4
Debt 1 APR (%)
Elasticity ↕ 0.00× — 10% change in this input affects Total debt balance by 0.0%.
ShowMath is the only calc site that surfaces this. Adjust the highest-leverage input first — that's where small moves create big results.
Chain payload (for the 3D constellation)
{
"slug": "debt-avalanche-vs-snowball",
"depth": 1,
"primitives": [
"debt-avalanche-calculator",
"debt-snowball-calculator",
"debt-payoff-comparison"
],
"composes": [],
"chain": [
{
"key": "total_balance",
"label": "Total debt balance",
"numeric": 46500
},
{
"key": "avalanche",
"label": "Avalanche (highest APR first)",
"primitive": "debt-avalanche-calculator",
"numeric": 7841.06357797545
},
{
"key": "snowball",
"label": "Snowball (smallest balance first)",
"primitive": "debt-snowball-calculator",
"numeric": 7841.06357797545
},
{
"key": "interest_delta",
"label": "Avalanche savings",
"numeric": 0
},
{
"key": "first_win_avalanche",
"label": "First debt eliminated (avalanche)",
"numeric": 0
},
{
"key": "first_win_snowball",
"label": "First debt eliminated (snowball)",
"numeric": 0
}
]
}The chain explained
Each step above corresponds to a primitive calculator. Click any to see the stand-alone version with its own explainer + sources.
- debt avalanche calculatorshipping soon
- debt snowball calculatorshipping soon
- debt payoff comparison
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