Work out what you need to set aside each month to hit a college savings goal, given what you've already saved and what you assume about returns.
Stated in today's dollars — inflation is applied below.
Average annual return, after fees.
Grows your target from today's dollars to the year you need it. Set to 0 to work entirely in today's dollars.
Required monthly contribution
$0 / month
The return assumption is the single biggest lever here — a point estimate hides how much it moves the answer.
This is a projection, not financial advice. It assumes a constant rate of return every single month. Real markets do not work that way, and the order the returns arrive in matters — a bad stretch right before you withdraw hurts far more than the same bad stretch fifteen years earlier. Treat the number as a starting point and revisit it yearly.
Contributions are assumed at the end of each month (an ordinary annuity), which is slightly conservative. The monthly rate is the true compounded twelfth root of the annual rate, not the annual rate divided by twelve.
Not modeled: account fees beyond whatever you've baked into the growth rate, state income-tax deductions for contributions, financial aid effects, scholarships, or any taxes and penalties on non-qualified withdrawals.
529 plans also carry aggregate contribution limits set per state — commonly somewhere between $235,000 and $600,000 in total per beneficiary. Check your own plan's limit if your target is near that range.