Child Savings by 18th Birthday Calculator
See what a child's savings will grow to by their 18th birthday from a starting balance plus a steady monthly deposit.
How it works
Months = (18 − age) × 12 · FV = start × (1+r)^n + monthly × ((1+r)^n − 1) ÷ r, where r = annual return ÷ 12
The balance at 18 has two engines: the head start you already saved, which compounds for the full remaining term, and the monthly deposits, each of which compounds for however many months are left after it lands. Because the youngest children have the longest runway, starting early matters far more than the size of any single deposit. The growth line shows how much of the final figure the market did for you rather than money out of your own pocket.
Worked example
For a 3-year-old with $2,000 saved and $150 added monthly at 6% a year, there are 15 years (180 months) to go. The result is about $48,500 — of which $29,000 is your own contributions and roughly $19,500 is growth.
Frequently asked questions
What account should I use for a child?
Common choices are a custodial UTMA/UGMA account, a 529 plan if the money is earmarked for education, or a plain high-yield savings account for short horizons. Each has different tax treatment and rules on when the child can access the money.
Does the child control the money at 18?
In a custodial account, control typically transfers to the child at the age of majority (18 or 21 depending on the state and account type). A 529 stays under the account owner’s control. Choose the vehicle with that hand-off in mind.
How much does starting earlier help?
Enormously. Because compounding is exponential, the first years contribute the most growth. The same monthly deposit started at birth rather than age 10 can end up worth roughly twice as much by 18.
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Educational estimate, not financial advice. Investment returns are not guaranteed.