Its official: Americans are not ready to retire.

According to recent retirement studies from both BlackRock and Merrill Edge, half of American investors realize they will have to delay their retirement dates and reduce their desired lifestyle in retirement because they havent saved enough.

And yet, many investors continue to suffer from an information gap thats preventing them from planning ahead.

Its common for investors to underestimate how much money they will need to cover themselves for their life when retired, said Frank Porcelli, head of BlackRocks U.S. Retail Business, in a statement accompanying the study’s results. Retirement today is not a single life stage and the new reality is that it could cover a 25-year period or longer during which time an individuals needs, goals and risk tolerance are likely to change.

Many investors are lowering their expectations for their retirement lifestyle, according to BlackRocks findings released Thursday. More than four in 10, or 42%, of nonretired investors say they have lowered their expectations for the kind of lifestyle they will have in retirement.  Half of investors say they either have pushed their retirement to a later date or are unsure about when they will retire.

Even those diminished plans could be at risk because of what BlackRock calls key information gaps that include an insufficient focus on planning and misunderstandings about the financial and demographic realities of retirement. Just 51% of nonretired investors surveyed by BlackRock agree that they know how much to save and more than one-third say they are not confident that they will achieve the annual income they will need for the time they expect to be in retirement.

At the same time, Bank of Americas Fall 2012 Merrill Edge Report shows that mass affluent Americans with $50,000 to $250,000 in investable assets dont feel theyve saved enough for retirement.

More than half of those surveyed say theyve saved less than $250,000 and theyre planning to retire later than they thought they would 12 months ago, according to the report. Top concerns include rising health care costs, concern that their retirement assets will not last throughout their lifetime, and that they won’t be able to afford the lifestyle they desire during retirement.

BlackRock found that the majority, 81%, of nonretired investors rate stocks as the most important retirement investment vehicle followed by bonds, at 60%, cash, at 57%, and annuities, at 48%.