Wealth & retirement · super (composes 4 primitives)
College funding engine
Pick the school cost today and the years until enrollment. We project tuition with 5% inflation, run 529 vs taxable vs UTMA growth side-by-side, calculate the monthly contribution to fully fund, and back out the loan amount needed if you only fund partially.
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Inputs
Result
Funding gap $159,289 — need $1,184/mo to close it (currently $350/mo).
Action: At current pace, you'll cover 36%. Either bump to $1,184/mo or plan for $159,289 loans.
- 1
Total cost (4 years, 5% tuition inflation)
$247,692
$32,000 × inflation × 4 years starting age 18
- 2
- 3
Taxable account (15% CG)
$84,502
Same growth, $3,900 long-term CG tax at withdrawal
- 4
UTMA (kiddie tax)
$85,802
Counts more heavily against EFC — typically the worst vehicle for college unless you want the kid to control it at 18/21
- 5
529 advantage vs taxable
$3,900
Tax-free growth + state deduction ≈ $182/yr
- 6
Monthly to fully fund
$1,184
Gap-closing contribution at 5% real return
- 7
Loan to cover gap (6.5%, 10-yr)
$1,809/mo × 120 mo
$217,044 total repaid ($57,754 interest)
Assumptions & notes
- Tuition inflation is held at 5% — historical CPI-tuition averaged 5.6% over 30 years but has cooled to ~3% recently.
- 529 also gets state income-tax deductions in 30+ states; we don't model those individually here.
- College finance: 12 years until enrollment. Increase risk in the early years and de-risk inside 5 years out.
10-year projection
529 balance trajectory
Multi-scenario comparison
What if — ±20% on one input
| Scenario | Child's current age | Headline | Δ vs baseline | Magnitude |
|---|---|---|---|---|
| −20% (cautious) | 4.8 | Funding gap $163,829 — need $1,105/mo to close it (currently $350/mo). | +$14,935 | |
| Baseline | 6 | Funding gap $159,289 — need $1,184/mo to close it (currently $350/mo). | 0 | |
| +20% (aggressive) | 7.2 | Funding gap $155,008 — need $1,281/mo to close it (currently $350/mo). | $-14,086 |
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 cost (4 years, 5% tuition inflation). Higher elasticity = bigger lever.
- 1
Years attending
Elasticity ↕ 1.41× — 10% change in this input affects Total cost (4 years, 5% tuition inflation) by 14.1%.
- 2
Annual cost today (tuition + room + board)
Elasticity ↑ 1.00× — 10% change in this input increases Total cost (4 years, 5% tuition inflation) by 10.0%.
- 3
Enrollment age
Elasticity ↑ 0.88× — 10% change in this input increases Total cost (4 years, 5% tuition inflation) by 8.8%.
- 4
Child's current age
Elasticity ↓ 0.29× — 10% change in this input decreases Total cost (4 years, 5% tuition inflation) by 2.9%.
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": "college-funding-engine",
"depth": 1,
"primitives": [
"529-savings-calculator",
"tuition-inflation-calculator",
"compound-interest-calculator",
"student-loan-calculator"
],
"composes": [],
"chain": [
{
"key": "future_cost",
"label": "Total cost (4 years, 5% tuition inflation)",
"primitive": "tuition-inflation-calculator",
"numeric": 247691.6879102763
},
{
"key": "529_projection",
"label": "529 projection (tax-free)",
"primitive": "529-savings-calculator",
"numeric": 88402.20729812447
},
{
"key": "taxable_projection",
"label": "Taxable account (15% CG)",
"numeric": 84501.8762034058
},
{
"key": "utma_projection",
"label": "UTMA (kiddie tax)",
"numeric": 85801.98656831203
},
{
"key": "529_tax_advantage",
"label": "529 advantage vs taxable",
"numeric": 3900.331094718669
},
{
"key": "monthly_full_fund",
"label": "Monthly to fully fund",
"primitive": "compound-interest-calculator",
"numeric": 1183.9522442884293
},
{
"key": "loan_alternative",
"label": "Loan to cover gap (6.5%, 10-yr)",
"primitive": "student-loan-calculator",
"numeric": 1808.6998315938492
}
]
}The chain explained
Each step above corresponds to a primitive calculator. Click any to see the stand-alone version with its own explainer + sources.
- 529 savings calculator
- tuition inflation calculatorshipping soon
- compound interest calculatorshipping soon
- student loan calculatorshipping soon
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