How to use this 529 calculator
Start with the Growth Projector. Enter your child's age, what you save monthly, and a return assumption — the single biggest driver of the final balance is the investment horizon, so starting early beats saving more later. The projector also shows your coverage rate against the inflation-adjusted 4-year cost and the exact figure for how much to save for college per month to close any gap.
Then solve precisely. The Monthly Solver inverts the math: give it your target (built from real College Board costs plus college inflation, or your own number) and it returns the required monthly contribution via the PMT formula. A common planning target is 50% of projected costs, with the rest from income, aid, and student contribution.
Don't leave state money on the table. The State Tax Benefit tab prices your state's deduction or credit in dollars per year — in high-limit states this is hundreds of dollars annually for doing nothing extra.
2025–26 average college costs (College Board)
Published total cost of attendance (tuition, fees, housing, food, books, transport, personal). Your school will differ — use the College Cost tab with a custom amount for precision. The cost of college in 18 years surprises most families: at 5% inflation, today's $30,990 public in-state year becomes roughly $74,600.
Worked examples
Newborn → public in-state university
$500/month for 18 years at 6% net of a 0.15% expense ratio grows to about $190,200. The projected 4-year cost is about $321,000, so coverage is roughly 59% — closing the gap needs about $785/month from day one.
Superfunding vs spreading $95,000
A $95,000 lump sum at birth growing at 6% for 18 years becomes about $271,000. Spreading the same $95,000 as $439.81/month yields about $167,600 — the front-loaded money earns roughly $103,000 more because every dollar compounds for the full 18 years. The catch: no additional gifts to that beneficiary for 5 years without touching your lifetime exemption.
529 vs taxable on $500/month
Over 18 years at 6%, the 529 reaches about $190,480 tax-free for education. A taxable account with the same inputs nets about $178,100 after 15% capital-gains tax on the gains — the 529 keeps roughly $12,400 more.
Methodology — the math, shown
Monthly compounding with end-of-period contributions. Monthly growth uses the effective monthly rate (1 + annual return)1/12 − 1, not annual ÷ 12. Monthly rate rm = (1+r)1/12 − 1, expense ratio subtracted from the annual return first:
Future value: FV = PV·(1+r)y + PMT·(((1+rm)12y−1)/rm)
Monthly solver (inverse): PMT = (Target − PV·(1+r)y) · rm / ((1+rm)12y−1)
College inflation: Costt = Cost0·(1+i)t; 4-year total sums years 0–3 from enrollment. State deduction saving = min(contribution, limit) × your marginal state rate; credits = rate × contribution capped at the statutory max. Taxable account = same growth, minus capital-gains tax on (balance − contributions) at withdrawal, with optional annual dividend drag. All estimates — returns are your assumption, never a promise.