But in high income countries 83 percent of young adults between 18 and 25 had an account with a formal financial institution, compared to 93 percent of adults 26-64.
The data was collected from more than 150,000 adults aged 15 and older in 148 countries and areas by Gallup for the World Bank Global Financial Inclusion database [Global Findex], funded by the Bill & Melinda Gates Foundation .
In East Asia and the Pacific, 61 percent of younger adults said they had a bank account, while just 58 percent of older adults did. In Europe and Central Asia, 44 percent of younger adults had an account, compared to 51 percent of older adults.
In Latin America and the Caribbean, 35 percent of younger adults used banks or financial institutions, while 44 percent of adults had an account, and in the Middle East and Asia only 14 percent of younger adults had a bank account, compared to 20 percent of adults in the regions.
The survey defined having an account as using a bank, credit union, cooperative, post office or microfinance institution. Women, the poor and rural residents in developing countries were least likely to have an account, but older women were 18 percent more likely to have an account than men.
The primary reason cited for the 700 million unbanked younger adults not having an account was a lack of money (29 percent) and the high cost of bank accounts (27 percent).
Nearly a quarter of unbanked young adults said family member had an account.
The survey conducted in 2011 had a margin of error of plus or minus 2 percentage points, Gallup said.