Seventy-one percent of the affluent say they have a written plan for their finances in retirement compared to 43 percent of those with less than $250,000 in assets. A majority of the affluent indicated they use detailed planning and calculation to estimate the percentage of their current household annual income needed to live on in retirement vs. about a quarter of those with less than $250,000 in assets.

While a majority of the affluent take a methodical approach to retirement planning, 73 percent of Americans with less than $250,000 in assets "guess" the percentage of their current household income needed to support them in retirement.

Further evidence of the confidence among affluent Americans is that 61 percent say they have "no financial fears" concerning their retirement because they are confident in their planning and preparation, which is about twice the level of those with less than $250,000 in assets.

Thirty-three percent of the affluent who were surveyed said they are afraid that doing all of the right things today will still not be enough to retire comfortably, compared to 52 percent of Americans with less than $250,000 in assets.  While one-quarter of  affluent Americans say they need to significantly cut back spending today to save enough for their retirement, half of those with less than $250,000 in assets indicate they will need to cut back spending.

When it comes to their current financial savings for retirement and expectations about finances in retirement, the affluent are more prepared than those with lower asset levels. In fact, the median amount already saved for retirement by the affluent is $500,000, which far exceeds the median ($60,000) amount that people with less than $250,000 in assets say they have saved for retirement.

Twenty-seven percent of the affluent cite health care costs as their primary day-to-day financial concern as compared with 16 percent of those with less than $250,000, who instead say "paying the bills" is their primary concern (43 percent). The affluent estimate out-of-pocket health care expenses in retirement at $60,000, and those with less than $250,000 estimate $49,000.

"Although the affluent are more financially prepared for their retirement, both groups have grossly underestimated the healthcare expenses they will need in retirement," said Wimbish. "They need to be more aware and plan for the real costs of healthcare in retirement."

More than half of affluent Americans are confident in the stock market as a good place to invest for retirement vs. 35 percent of those with less than $250,000 in assets.

One-third of Americans with less than $250,000 in assets will end up working in retirement because of financial necessity, the study found, compared to just 9 percent of the affluent.

Forty-two percent of affluent Americans said they expect to work into retirement because they want to and not because of financial need compared to 32 percent of non-affluent Americans.  One-quarter of non-affluent Americans agree they will need to work until they are at least 80 to  afford retirement, despite the fact that only 36 percent think they will be mentally or physically capable of being a productive employee in their 80s.

Affluent Americans contribute more to their 401(k) plans than their non-affluent counterparts and the affluent also expect Social Security to play less of a role in their retirement than those with less than $250,000 in assets.

The telephone survey of 1,800 adults aged 25 to 75 was conducted on behalf of Wells Fargo by Harris Interactive between July 9 and Sept. 7, 2012.

Wells Fargo & Company is a nationwide, diversified, community-based financial services company with $1.4 trillion in assets.