Staff who arrive late at work are costing the economy £9 billion a year, a new survey suggests.
More than half (56%) of all employees admit failing to attend meetings and other work events on time at least once a week, it claimed.
One in 10 people revealed they had been late for a job interview, while 11% said poor time keeping had contributed to the loss of a potential new client.
Almost a quarter of workers (23%) said they perform badly in meetings after arriving late, while nearly half (48%) said this adversely affected the performance of their colleagues.
Meanwhile 82% of people said they believed being late was unprofessional, according to the survey of 1,000 employees by Heathrow Express.
The study found an average of 590,000 workers in the UK show up late every day.
Each late employee loses an average of 97 minutes per month which costs British employers £305 per head every year, it added.
The main excuse for being late was traffic problems caused by road works (41%). Other reasons included public transport delays (29%), unforeseen circumstances such as someone being unwell (25%), bad weather (18%), sleeping through the alarm (14%) and leaving something behind (12%).
Some 63% of workers admitted they were affected by the stress of being late, while 39% said the after-effects negatively impacted on their entire day.
Nearly a fifth (19%) said their late arrival had resulted in a disastrous meeting.
Three quarters of employees (74%) revealed that being late made them feel guilty and nearly half (48%) agreed that people lost respect for them after failing to show up on time.
The research also found that it took an average of 49 minutes for people to feel calm and in control after a late arrival.
A total of 46% of those surveyed admitted that the stress from being late lasted between 10 and 60 minutes, and this had a detrimental effect on their concentration and interaction with colleagues.
Behavioural psychologist Dr Cecilia d'Felice said: "The cost of lateness to the economy is enormous, but potentially even more serious is the detrimental impact it can have on workplace performance, team morale and productivity.
"Encouragingly, no one likes being late as it makes them feel guilty, but this feeling can have a negative impact on workplace performance in the longer term. The fact that people admit their own lateness affects the performance of those around them is of concern as the example they set to other members of staff around them is critical."
Heathrow Express managing director Keith Greenfield said: "Time is money and when it comes to making business journeys, punctuality and speed are crucial."
Researchers used the average hourly pay rate of British employees (£15.67), the total working population figures and the average number of minutes late to work, work meetings and work events per person (17.7) to calculate the estimated cost of late workers to the economy.