How this calculator works
This uses the future value of an annuity formula with monthly compounding. In plain English: it figures out how much you need to put in every month so that your contributions plus investment growth equals your target by the time your kid turns 18.
The default 7% return is a conservative estimate for a stock-heavy 529 portfolio over 10+ years. If your kid is closer to college age, you'd use a more conservative number (4-5%) since your money has less time to recover from market dips.
What this doesn't include
College cost inflation. College costs rise about 3-5% per year. A school that costs $100K today will cost $135-180K in 15 years. Consider increasing your target to account for this.
State tax deductions. Many states offer a tax deduction for 529 contributions. That effectively reduces your cost. The tax savings line above is a rough estimate. Check your state's specific deduction.
Financial aid impact. 529 assets are counted as parental assets on the FAFSA, which has a smaller impact on aid eligibility than student assets. This is generally favorable.
Next steps
Once you know your monthly number, the next question is which 529 plan to use. See our comparison of the best 529 plans with fees, investment options, and state tax benefits compared side by side.
If saving for college is one of many financial goals you're juggling, the Money Milestones Before 35 checklist helps you prioritize where each dollar should go first.
