The simplest version of the question is what happens if a child starts with $1,000 and leaves it invested until age 18. Public estimates have used a long-run stock market assumption that turns that into roughly $5,800 by adulthood.
That example is useful because it shows what time alone can do. It is also incomplete, because many families will want to add their own money once the account is open.
A modest monthly contribution can change the ending balance far more than parents expect. Small gifts repeated for years usually matter more than one dramatic deposit made once.
The child's current age matters too. A newborn has much more runway than a ten-year-old, which is why families with babies are paying especially close attention to the 2026 window.
That is why a growth calculator helps. Parents do not need slogans about compounding. They need a realistic way to test starting age, return assumptions, and repeatable family contributions.
