What is this calculator for?
Your daughter just turned 2, you have $4,000 set aside for "her future," and your in-laws keep asking about whether you've started a 529. You vaguely know it's a tax-advantaged college savings account. The 529 plan calculator shows you the projected balance at age 18 based on your contribution rate, plus the tax savings compared to a regular taxable account.
A 529 plan is a state-sponsored, tax-advantaged investment account for education expenses. Contributions are after-tax (no federal deduction except in some states), grow tax-free, and withdrawals are tax-free if used for qualified education expenses (college tuition, fees, room, board, books, K-12 tuition up to $10K/year, student loan repayment up to $10K lifetime, apprenticeship programs). Non-qualified withdrawals are taxed as ordinary income plus a 10% penalty on the growth portion.
Most US states sponsor their own 529 plans; you can use any state's plan regardless of where you live. 35 states offer state income tax deductions or credits for contributions to the state's own plan (Pennsylvania, Arizona, Kansas, Missouri allow deductions for ANY state's 529). The average state deduction is $5,000-10,000 of annual contributions, generating $250-500/year in state tax savings depending on the state's rate.
This calculator projects 529 growth at typical investment returns (6-7% for age-based portfolios that shift more conservative as the beneficiary approaches college age), shows the tax savings vs taxable account, and compares against alternative funding strategies.
How to use this calculator
Enter the beneficiary's current age (the child or future student). The calculator projects to age 18 (typical college enrollment) by default; you can adjust if planning for earlier (K-12 use) or later (graduate school) target dates.
Enter your initial deposit (lump sum starting the plan) and monthly contribution going forward. Many parents start with a baby-shower gift lump ($1,000-5,000) and add monthly contributions ($100-500). Grandparents often contribute to grandchildren's 529s — these contributions count against the grandparent's gift tax annual exclusion ($19,000 in 2026).
Set your investment return rate. Age-based 529 portfolios (the most common) automatically rebalance from aggressive (stock-heavy, expected return 7-10%) to conservative (bonds and cash, expected return 3-5%) as the beneficiary nears college age. For long-horizon projections, use 6-7% as a blended average. Static portfolios (you control the allocation) allow more aggressive returns but with higher volatility.
Enter your state for state tax deduction calculation. The calculator applies your state's deduction rules and produces a tax-savings figure to compare against a taxable account approach.
Understanding your results
The calculator returns projected 529 balance at target date, total contributions, investment growth, state tax savings over the contribution period, and a comparison vs taxable account showing the 529's tax-advantage benefit.
How to read it. A 2-year-old starts with $4,000 lump + $300/month for 16 years at 7% real return: ending balance ~$118,000. Total contributions: $61,600. Investment growth: $56,400 (none of which is taxed if used for qualified expenses). Taxable account equivalent: same contributions, growth taxed at ~15% capital gains over the holding period = roughly $108,000 ending balance. The 529's tax advantage: ~$10,000 of additional buying power for college expenses.
The state-deduction multiplier. New York allows $10,000/year 529 deduction at 6.85% state rate = $685/year tax saving. Over 16 years that's $11,000 in state-level tax savings on top of the federal tax-free growth. Combined federal + state advantage of 529 vs taxable can be 15-25% of total contributions over long horizons.
The risk of over-funding. If your child ends up with full scholarships or doesn't attend college, the 529 balance becomes harder to use. Workarounds: change beneficiary to a sibling, cousin, niece/nephew, even yourself for graduate school. New 2024 rule: up to $35,000 of unused 529 funds can be rolled over to the beneficiary's Roth IRA (subject to annual contribution limits and other conditions). For families uncertain about college plans, modest 529 contributions are safer than aggressive ones — you can supplement at the last minute via brokerage account if needed.
The financial aid interaction. Parent-owned 529 balance counts at 5.64% toward Expected Family Contribution. Student-owned 529 balance counts at 20%. Always make 529 plans parent-owned for college-bound kids planning to file FAFSA. Grandparent-owned 529s previously counted heavily against aid but post-2024 FAFSA changes mostly eliminated that penalty.
A worked example
James and Lin have a 5-year-old daughter, Sophia. They're moderate earners — combined $145,000 in suburban Denver. They have $2,500 already saved and want to fund Sophia's college as much as possible while balancing other priorities.
They open a 529 with their initial $2,500 plus $250/month contributions. Colorado offers a state income tax deduction up to $25,000/year for in-state 529 contributions — they easily fit under the cap. State tax savings: $250 × 12 × 4.4% = $132/year in state tax savings.
13 years later: Sophia is 18. Account math: $2,500 lump grown over 13 years at 6.5% real = $5,668. Plus $250/month contributions of $39,000 total, grown average over the period = roughly $61,000 in contribution-growth terms. Combined balance: $66,668 in today's dollars (Sophia's freshman year, 2034 in nominal but using real growth assumption).
Sophia attends Colorado State University (in-state public). 4-year cost: $112,000 nominal (about $90K in 2026 dollars). The 529 covers $67K of that; the family needs $23K from current cash flow + Sophia's part-time work + small federal loans. Manageable.
Alternative scenarios. If Sophia gets a full-tuition merit scholarship: 529 has $67K with no required use. Options: (a) use for room/board/books (still qualified), (b) change beneficiary to her younger brother (born 2025) for his future use, (c) save for her graduate school, (d) under new 2024 rules, roll over up to $35K to her Roth IRA over multiple years.
If they hadn't started the 529 and instead used a taxable brokerage account: same contributions, similar returns, but capital gains tax (~15% federal + 4.4% Colorado) on growth at withdrawal. Effective tax drag over 13 years reduces ending balance to roughly $58,000 — about $9,000 less. The 529 tax advantage represents one extra year of in-state public college tuition.
Related resources
For broader college cost planning, the College Net Price Calculator. For need-based federal aid, the Pell Grant Estimator. For loan-side context, the Student Loan Calculator. For compounding growth math underlying 529 projections, the Compound Interest Calculator. The Saving for College independent rating service compares all 50 state plans on fees, performance, and tax benefits.