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A 529 plan grows in two parts: the balance you already have keeps compounding, and each monthly contribution compounds from the month you make it. Grow the balance at the annual return, grow the monthly deposits at the monthly rate (the annual return ÷ 12), and add them. Starting with $5,000 and adding $300 a month at a 6% return for 18 years grows to about $130,000, of which roughly $70,000 is money paid in (your starting balance plus contributions) and the rest is investment growth.

529 Calculator — college savings growth

%

$300/mo at 6% for 18 years.

Balance at college$130,477.65
Total paid in
$69,800.00
Investment growth
$60,677.65

Quick examples

How it's calculated

  1. Balance grown + monthly contributions grownFV=B(1+r)t+d (1+r/12)12t−1r/12\text{FV} = B(1 + r)^t + d\,\frac{(1 + r/12)^{12t} - 1}{r/12}
    years
    = 18
    130,477.65
Balance at college$130,477.65

How it works

A 529 is a tax-advantaged plan for education savings: contributions grow tax-free and are tax-free when spent on qualified education costs. Projecting the balance is compound-interest math in two pieces (per LibreTexts):

  • The current balance grows to B × (1 + r)ᵗ over t years.
  • The monthly contributions compound at the monthly rate i = r ÷ 12 across n = 12 × t months, growing to d × ((1 + i)ⁿ − 1) ÷ i — the future value of a monthly annuity.

Adding the two gives the projected balance when college starts. The calculator splits the result into total paid in (your starting balance plus every contribution) and investment growth, so you can see how much of the fund comes from your deposits versus compounding.

The return is an assumption — 529 investments (often age-based portfolios) shift toward safer assets as college nears, so real returns vary. Starting early gives compounding the most time to work.

Worked example

Starting with $5,000, adding $300 a month, at a 6% return for 18 years: the balance grows to about $14,300 and the monthly contributions grow to about $116,200, for a projected total near $130,000. Of that, $69,800 was paid in ($5,000 starting balance + $300 × 216 months) and the rest is growth.

Frequently asked questions

How much will my 529 be worth?

Grow your current balance and your monthly contributions at your expected return and add them. For $5,000 plus $300 a month at 6% over 18 years, that is roughly $130,000.

What is a 529 plan?

It is a tax-advantaged college-savings account. Money grows free of federal tax and is not taxed on withdrawal when used for qualified education expenses such as tuition, fees and room and board.

How much should I save in a 529?

Enough to cover your target share of projected college costs. Work backwards from an estimated cost, or try different monthly contributions here to see what balance each reaches by the time college starts.

What return should I assume?

Many 529s use age-based portfolios that start growth-oriented and grow more conservative as college nears, so a blended long-run return of 5–7% is a common planning assumption. Lower it for a shorter horizon.

Are 529 contributions tax-deductible?

Not federally, but many states offer a state income-tax deduction or credit for contributions to their plan. The growth and qualified withdrawals are federally tax-free.

What if my child doesn't go to college?

A 529 can often be used for trade schools, apprenticeships and some K–12 costs, transferred to another beneficiary, or (within limits) rolled to a Roth IRA. Non-qualified withdrawals of earnings are taxed and penalized.

How we know this is right

Last reviewed
Aug 9, 2026
Precision
Rounded to 2 decimal places.
Read our methodology

Sources