Ballooning health care costs mean that more retirement nest eggs may be at risk, and a common retirement-savings metric may be luring Americans into a false sense of security.

So-called "Income-Replacement Ratios," or IRRs, are a broadly used benchmark for determining if individuals' assets will be able to last throughout their retirement years.

The rule of thumb typically says that amassing about 75% to 85% of an individual's pre-retirement income per year will allow for an equivalent lifestyle in retirement as during one's working years.

Read the entire article at Investment News.