Although most bosses assume the rank-and-file will have downtime every day, employees waste about twice as much time as their employers think, according to a new survey by Salary.com and America Online.

Employees spend an average of 1.86 hours per eight-hour workday on something other than their jobs, not including lunch and scheduled breaks, the survey found. Based on those averages, employee time-wasting costs U.S. employers an estimated $544 billion in lost productivity each year.

More than half (52%) of the 2,706 people surveyed admitted that their biggest distraction during work hours is surfing the Internet for personal use. Other distractions cited by respondents included socializing with co-workers (26.3%), running errands outside the office (7.6%) and spacing out (6.6%).

The good news for employers is that time-wasting appears to be decreasing. In a similar survey conducted in 2005, U.S. workers admitted to squandering 2.09 hours per 8-hour workday. Thirty-three percent of those polled said they waste time at work because they don't have enough work to do, while 23.4% wasted time because they felt underpaid

The 2005 survey also found that older employees wasted less time at work than their younger counterparts. People born between 1950 and 1959 waste 0.68 hours at work each day, while those born between 1980 and 1985 admit they waste 1.95 hours.