Workers in Britain put in unpaid overtime worth around billion a year, a report by the main trade union body, the TUC, said here Friday.
The TUC released the details to mark its 14th annual Work Your Proper Hours Day to highlight the extent of unpaid work.
Statistics by the TUC show one-in-five people in Britain do unpaid overtime. London tops the TUC chart for unpaid overtime, with 880,000 workers, a quarter of the capital's workforce, doing some work for free.
Nearly 5 million people put in an average of 7.4 hours a week in unpaid overtime during 2017, equivalent to missing out on pay averaging almost ,800 each, according to the report.
To mark the day, the TUC asked all workers to take a proper lunch break and leave for home on time, calling on bosses to consider how to move away from over-reliance on unpaid overtime.
TUC General Secretary Frances O'Grady said: "Lots of us are willing to put in a bit of extra time when it's needed. But it's a problem if it happens all the time. So today we're saying to workers, make sure you take a proper lunch break and go home on time."
"We're asking managers to leave on time too. Good bosses know that a long-hour culture doesn't get good results. And the best way to lead is by example."
The TUC analysis also found that while public sector employees make up 25 percent of all employees, they account for almost 40 percent of all unpaid overtime.
O'Grady added: "Public sector workers are more likely to work extra hours unpaid. It's a mark of how dedicated our public servants are, and it's kept our schools and hospitals running through years of funding cuts."
"But public service workers have also had eight years of real pay cuts, so they are being forced to do more for less. It's time the government gave them the fully-funded pay rise they have earned."