Custodial Account Calculator: Project a Child's Account
Project how a custodial account could grow for a child, from a starting balance and steady monthly contributions until they come of age.
Adjust the inputs and select Calculate for a full breakdown.
Year-by-year growth schedule
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Future value | Total contributions | Total interest earned |
|---|---|---|---|
| $2k · $150/mo · 7% · 18yr | $71,633.23 | $34,400.00 | $37,233.23 |
| $0 · $200/mo · 8% · 15yr | $69,207.64 | $36,000.00 | $33,207.64 |
| $10k · $100/mo · 6% · 12yr | $41,522.52 | $24,400.00 | $17,122.52 |
| $5k · $300/mo · 7% · 18yr | $146,779.00 | $69,800.00 | $76,979.00 |
How This Calculator Works
Enter the current balance, the average annual return you expect, the years until the child reaches the age of majority, and your monthly contribution. The calculator compounds the balance monthly and adds each contribution, showing the projected balance and the growth.
The Formula
Future Value with Regular Contributions
P = starting amount, PMT = monthly contribution, r = monthly rate (annual ÷ 12), n = number of months
Worked Example
With $2,000 saved, $150 added monthly, and a 7% average return over 18 years, a custodial account reaches about $71,600. Contributions account for $34,400; investment growth supplies the other $37,200.
Key Insight
A custodial account is flexible — the funds can be used for anything that benefits the child, not just education. The trade-off is control: at the age of majority the account legally becomes the child's, to use as they choose.
Frequently Asked Questions
What is a custodial account?
A custodial account, set up under UGMA or UTMA law, holds investments for a minor. An adult custodian manages it until the child reaches the age of majority.
How is a custodial account different from a 529?
A 529 must be used for education to keep its tax benefit. A custodial account can fund anything benefiting the child, but its growth has no comparable tax shelter.
Who controls the money?
The custodian manages it for the child's benefit until the age of majority. After that, the account belongs to the child outright, to use as they wish.
Is the growth taxed?
Yes. Investment income in a custodial account is taxable, and beyond a threshold the child's unearned income can be taxed at the parents' rate under the kiddie tax.
Does a custodial account affect financial aid?
It can. Because the account is the child's asset, it is generally weighed more heavily in financial-aid calculations than a parent-owned 529 plan.
Related Calculators
Data Sources & Benchmarks
This calculator draws on 3 independent, dated sources. The starting values for expected annual return are taken from the benchmarks below and refresh whenever the snapshots are updated.
Methodology & Review
The projection compounds the balance monthly at a constant expected return and adds a fixed monthly contribution. It excludes fees and the so-called kiddie tax on investment income.
Written by Ugo Candido · Last updated May 17, 2026.