Ask average American families how much money they will need to save for retirement and you often receive answers at or around $1 million, but 71 percent of registered investment advisers contacted for a new a new survey don't believe that's enough. In fact, most believe families need to be saving double and, in some cases, more than triple that amount.

"While there are no definitive answers on how much money various generations will need to save for retirement, it is clear that the majority of RIAs feel the $1 million goal is not enough for most families," says Craig Hogan, director of customer intelligence, customer relationship management, and reporting for St. Louis-based Scottrade Inc.

The survey asked RIAs for their opinions about the current investment habits of Americans and how much money they felt was needed for typical families to save for retirement.

Questions were broken down by generations to determine RIAs' opinions on average investment goals, in today's dollars, for varying ages.

The recommended goals are the greatest for Generation Y, or those 18 to 26 years old. More than three-quarters of advisers suggest a goal of at least $2 million, and more than 40 percent believe that Generation Y should be targeting more than $3 million in retirement funds.

RIAs also suggest loftier goals for Generation X, between 27 and 42 years of age. Forty-six percent of survey respondents said they believe Generation X should at least double the $1 million goal and save between $2 and $3 million. Twenty-two percent suggest an even higher amount—a goal of more than $3 million.

As for baby boomers, between 43 and 64 years of age, 35 percent of RIAs surveyed said they'll need between $2 million and $3 million to retire, and 13 percent believe they'll need more than $3 million. Thirty percent recommend a retirement goal between $1.5 million and $2 million.