College Savings Planner

College Savings Planner — guide & how to use

What it does

This planner answers the question parents and grandparents actually ask: how much do I need to save per month so a 529 fund covers my target school? It does the math a generic calculator skips — it inflates every college year's cost to its own enrollment year, grows your existing balance and contributions at your expected return (compounded monthly), and scales the goal by the percent of cost you want to cover. Enter a monthly amount you already plan to save to flip into "will I make it?" mode and see your projected surplus or shortfall. Everything runs privately in your browser, free.

How the math works

1. Inflate each year: year k of college starts (years-until-enrollment + k − 1) years out, so its cost = today's cost × (1 + inflation)^that exponent. Freshman year is cheapest; senior year costs the most.
2. Sum & scale: add up all the inflated years to get the gross total, then multiply by your cover-percent to get the covered goal as a lump sum at the start of college.
3. Grow what you have: your current 529 balance compounds at the monthly return until enrollment.
4. Solve for the monthly: the remaining gap is solved with the sinking-fund (ordinary annuity) formula — the level monthly deposit that compounds to exactly fill it. The figure is rounded up to the cent so the plan never falls short.

Worked example

Newborn, in-state public school: cost today $24,920, 18 years until enrollment, 4 years to fund, cover 100%, $0 saved, 6% return, 5% cost inflation:

1. Freshman year cost: $24,920 × (1.05)^18 ≈ $59,968 — a 2.41× inflation multiplier. Each later year inflates further (sophomore at ^19, etc.).
2. Covered goal: summing all four inflated years gives roughly $258,000 in future dollars (× 100% covered).
3. Required monthly: with $0 saved and 18 years (216 months) at 0.5%/month, the sinking-fund formula returns about $665/month.
4. Where it comes from: roughly $144,000 of that goal is your own contributions and the rest is investment growth — which is why starting early matters so much.

(The tool carries full precision and rounds only the displayed figures, so hand-rounded steps can differ by a few dollars.)

How to use it

1. Enter the target school's annual cost today, the years of college to fund, and the percent of cost you want to cover (try the 50 / 75 / 100 presets).
2. Set years until enrollment, your current 529 balance, and your expected return and cost inflation assumptions.
3. Read the headline monthly amount needed — or enter a monthly amount you already plan to save to check whether you're on track.
4. Use Copy share link to save or send the exact scenario; the link reopens with all your inputs prefilled.

Accuracy notes & common mistakes

• Inflate every year separately. Multiplying today's cost by four years undercounts the goal badly over an 18-year horizon — a $24,920 year becomes ~$60k, and senior year costs even more.
• Compound the return monthly. The annual return is divided by 12 for the monthly rate; using the annual rate directly massively overstates growth.
• Grow your existing balance first. Your current 529 compounds on its own until enrollment, reducing the monthly contribution needed — subtract it after growing it.
• Lump-sum simplification (conservative): the default targets the full covered cost as a single amount at the start of year 1. In reality you pay over several years, so money for later years keeps growing — meaning the default slightly overstates the monthly needed. That's a safe direction to err.
• Sticker vs. net price: published costs are sticker prices; net price after grants and scholarships is usually lower. The cover-percent input is how you account for expected aid — it's a blunt instrument.
• Use total cost of attendance, not tuition alone. Room, board, and fees are a big share families often forget.
• Nominal, not inflation-adjusted dollars, and the model already inflates cost separately — don't also use a "real" (inflation-adjusted) return or you'll double-count inflation.
• Out of scope: 529 contribution limits, state tax deductions, and the $35,000 lifetime 529-to-Roth IRA rollover. 529 growth is federal-tax-free for qualified expenses; enter a net-of-fee return.

Frequently asked questions

Educational planning estimate only — not financial advice and not a guarantee of investment performance. Markets vary; a fixed assumed return cannot predict actual 529 results, which can be negative in any year. College Board published costs are sticker prices; net price after aid is typically lower. Recent years (2024-25) saw unusually low published-tuition increases (~1.3% in-state public, ~2.2% private). Source: College Board Trends in College Pricing & Student Aid 2025; standard sinking-fund (ordinary annuity) finance math.

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