529 Contribution Calculator
A 529 contribution calculator answers a single practical question: how much do I need to put in each month to actually cover college? This tool projects future college costs using a realistic tuition inflation rate, grows your existing 529 balance at your expected investment return, and then solves backwards for the monthly contribution required to close the gap.
Why contributions matter more than returns
Over a typical 18-year savings window, the single biggest lever is how much you deposit, not what return you assume. A family that saves $400/month at 6% ends with about $155,000. Bumping returns to 8% only nudges that to $185,000. Doubling contributions to $800/month at 6% doubles the end value to $310,000. The return input matters, but contributions dominate.
How this 529 contribution calculator projects cost
College cost of attendance is inflated forward from today's dollars to each future year your child will attend. This matters because tuition historically grows 4-6% per year, nearly double general CPI. A school that costs $30,000 today will cost about $50,000 when a 5-year-old starts college 13 years later at 4% inflation, or about $63,000 at 6% inflation. The calculator sums all funded years into a single lump-sum target at the start of college.
Monthly contribution formula
The required monthly deposit is solved from the future value of annuity equation: PMT = (target - currentFV) x r / ((1+r)^n - 1), where currentFV is your current balance grown at the monthly rate for n months. For a target of $200,000 in 15 years with $5,000 already saved at 6% return, the solution is about $648/month.
Tax advantages of the 529
Every dollar of growth in a 529 plan is federal-tax-free when spent on qualified education expenses (tuition, fees, books, supplies, room and board, and up to $10,000/year of K-12 tuition). Most states also offer an annual state income tax deduction or credit for contributions, up to a per-taxpayer or per-beneficiary cap that varies by state. Tax-free growth can effectively add 1-2% to your after-tax return compared to a taxable brokerage account, shrinking the required contribution.
Realistic assumptions
For the default inputs this calculator uses: 5% tuition inflation (mid-range historical), 6% portfolio return (moderate age-based 529 allocation), and 100% of cost coverage. You can dial coverage down to 50-70% if you plan to cover the rest from current income, scholarships, or student loans. Most financial advisors suggest saving for 50-75% of cost rather than 100% so you preserve flexibility if plans change.