The findings are being released at a time when Americans' term savings are under scrutiny.
Average retirement account balances have grown rapidly in recent years, thanks in part to a strong stock market. And the number of Americans with 401(k) accounts has risen.
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That shift "shows that the 401(k) plan can indeed build a significant nest egg," said Sarah Holden, senior director of retirement and investor research at the Investment Company Institute (ICI). The institute has collaborated with the Employee Benefit Research Institute to analyze how much an individual with 401(k) accounts available throughout his or her career would actually save. The conclusion, Holden said, was that even when people are less than perfect savers, a 401(k) can indeed provide significant income in retirement.
But the growth in 401(k) balances has only helped those who have retirement savings, and almost 40 million working age households do not, according to the National Institute for Retirement Security. (That institute found that about half of the households without retirement savings are headed by someone aged 45 to 65, though the ICI, in its own study, found that roughly eight out of 10 households nearing retirement have some retirement assets.)
Sadowsky pointed out that a third of retired Americans get 90 percent or more of their income from Social Security.
"Throughout our history, we just have not done a good job of saving," he said. "If you don't have an emergency fund and a plan in place with multiple scenarios planned out, there is certainly going to be fear that you are not going to be able to respond in a timely manner" to a financial disruption.
Read MoreTime to call it: The 401(k) is a failure