"Many Americans know what they should do, but don't do it -- and that's a costly mistake for millions of people," said Bankrate, Inc. president and CEO Elisabeth DeMarse. "No one would want to show this report card to their parents."

Bankrate created a test of financial literacy using 12 basic 'planks' that Americans should know and put into practice, said DeMarse. Questions included, 'Have you prepared a will?' and 'Have you started an emergency fund?' To create a grade scale, Bankrate converted the 12 questions into a 100-point scale.

So who is your financially literate client? Your "A" client, based on Bankrate's statistics, is over 50 years old, married with children, maintains a higher household income (average $63,500), uses the Internet to manage his or her finances, plans carefully when making decisions, and is a "saver."

In contrast, a financially unfit American is about 41 years old, maintains a $43,000 household income, is most likely unmarried with children, and most likely considers himself or herself a "spender".

Overall, Bankrate found that gender and formal education play no role in financial literacy -- but age and attitude do. Older Americans tended to be smarter about their money moves than younger Americans. Financially fit Americans express confidence in money management and feel in control when dealing with their finances.

According to DeMarse, there is an attitude and action gap when it comes to many of the 12 steps to financial literacy. This gap is holding back many Americans from forging the financial future that they want. For example, 59 percent of Americans feel they are in control of their personal finances, yet 58 percent indicated they had not refinanced their mortgage during this last year of record low rates and 59 percent did not know how much life, auto or health insurance they should carry.

Financially literate Americans also enjoy better rates. "Americans who scored an A or a B on our Financial Literacy Test are enjoying of one point less on their mortgage than those who scored F," said DeMarse. "On a $150,000 mortgage, that difference represents a savings of $103.68 a month."

Overall, only 10 percent of Americans received an "A" in Bankrate's financial literacy report card, 16 percent received a "B", 19 percent a "C", 20 percent a "D", and 35 percent received a failing "F."

Noteworthy is how respondents ranked their money woes. When asked to name their worst financial fears from a list of 10 choices, 79 percent of respondents said they fear that terrorism will weaken the U.S. economy, while roughly half is concerned about their lack of savings.  Roughly one in three Americans are worried about losing their jobs, that their employer will decrease their benefits, that their home will lose value, or that they will not be able to pay their mortgage or rent. And 55 percent fear they do not have enough money put away for an emergency -- but only 40 percent are actually doing it all the time.

Read the full Bankrate.com's Financial Literacy benchmark survey