LondonOffices.com quizzed more than 500 workers, all of whom worked 09:00 to 17:30 jobs, to find out what times they mentally clocked on and off at work.
Researchers found nearly three quarters of an hour was lost in the morning, with 09:43 coming out as the average time office workers confessed to buckling down to work.
More than half an hour was wasted in the afternoon with the average respondent claiming to switch-off at 16:52.
Many respondents cited that they filled this time with mundane activates such as chatting to colleagues, organising papers and even eating breakfast at their desk.
However, some claimed that their hectic family life meant the boundaries between their job and home were becoming increasingly blurred at the start and end of each day.
In fact, the study found that 74 per cent of office workers started planning their evening activities after 15:00.
Added together this represents an average loss of one hour and 21 minutes of productivity each day per employee.
In a 50-person office this represents a loss of 67.5 working hours each day and 337.5 hours, each week the same as one worker being absent for a fortnight.