Two Moving Targets, Not One
Planning for college costs is unusual among savings goals because both sides of the equation move. Your 529 balance grows with contributions and investment returns — that part is familiar from any retirement or savings projection. But the target itself, the actual cost of college, is also moving, and historically it has often moved faster than general consumer prices. A projection that only accounts for your savings growth while assuming today's tuition number stays fixed will systematically overstate how prepared you are.
How the Savings Side Works
The 529 balance side of the calculation uses standard monthly compounding: each month, the existing balance earns a fraction of the annual return rate, and then that month's contribution is added on top. Over many years, this produces the familiar exponential-looking growth curve of compound interest — the same method used for retirement and other long-horizon savings goals. Two inputs drive most of the outcome: how much time is left before college starts (more time means more months of compounding), and the assumed annual return, which should reflect the actual asset allocation of your 529 account, not just an optimistic guess.
How the Cost Side Works
The cost side takes today's estimated annual college cost and compounds it forward by an assumed college-cost inflation rate — separately from any general inflation assumption, since these two figures often diverge. Critically, the cost calculation shouldn't stop at the year college starts. If your child attends a four-year program, the second, third, and fourth years of tuition are also further in the future and should be inflated further forward from today, not treated as if they cost the same as year one. A calculator that only projects the cost of the first year of college and multiplies it by four will meaningfully understate the total bill.
Reading the Gap
Once both sides are projected, the comparison is simple subtraction: projected 529 balance minus total projected college cost across every year of attendance. A positive number is a surplus — room to spare, or an opportunity to redirect contributions elsewhere. A negative number is a funding gap, and it tells you concretely how much more you'd need to either save monthly, or plan to cover through other means (financial aid, scholarships, current income, or loans) when the time comes.
Why the Inflation Assumption Deserves Scrutiny
The college-cost inflation rate you choose has an outsized effect on the projected gap, precisely because it compounds over many years just like investment returns do. A one or two percentage point difference in this assumption, projected out over a decade or more, can shift the total cost estimate by tens of thousands of dollars. Rather than treating any single number as fact, it's worth running the calculation with a conservative estimate and a more optimistic one, so you understand the range of outcomes rather than anchoring on one point estimate.
Using the Result
If the projection shows a gap, the most direct lever is usually the monthly contribution — small increases made early benefit from more years of compounding than the same increase made later. If a gap remains after reasonable contribution adjustments, it's worth having that conversation early: many families end up funding college through a mix of 529 savings, financial aid, scholarships, and some combination of current income or loans, and knowing the likely size of that gap years in advance makes every one of those options easier to plan for.
Frequently Asked Questions
It compounds today's estimated annual cost forward by your assumed college-cost inflation rate for every year of enrollment separately — year 1 is inflated to the year college starts, year 2 is inflated one year further, and so on. This avoids understating the total bill, since later years of college are further in the future and subject to more cumulative inflation.
Yes — the 529 College Savings Calculator projects your 529 balance at college start age using monthly compounding, projects total college cost inflated forward across every year of attendance, and shows the exact dollar funding gap or surplus between them. It's a one-time $6.99 purchase — no subscription, no account required.
Use a rate consistent with your 529 plan's actual investment allocation — many 529 plans use age-based portfolios that shift from stock-heavy to more conservative as college approaches, so a single flat rate is a simplification. Check your plan's own historical performance and target allocation as a starting reference point.
College costs have historically often risen faster than general consumer prices, so using a single general inflation rate for both your investment growth assumptions and your tuition projection can understate future costs. The calculator lets you set the college-cost inflation rate independently so you can model that historical pattern as an assumption you control.
No — this is a pre-aid, pre-scholarship projection comparing your savings trajectory against sticker-price college costs. Financial aid, scholarships, tax credits, and state 529 tax deductions can all reduce the real out-of-pocket gap, but they're too individual and unpredictable to build into a generic projection.