The total amount of unpaid overtime worked last year was 1,968 million hours - worth £29.2 billion to the UK economy - and equivalent to a million extra full-time jobs.
If workers who regularly put in unpaid overtime worked all their hours from the start of the year, the first day they would get paid would be Friday 24 February.
In the run-up to this date the TUC will publish information and advice for staff and their bosses to try and cut out these unpaid hours at work. The TUC will call on employers to mark Work Yours Proper Hours Day by thanking staff for the extra hours they're putting in.
The TUC analysis of official figures shows that 5.3 million workers put in an average of 7.2 hours of unpaid overtime per week last year, worth around £5,300 a year per person.
Whilst reducing the amount of unpaid overtime would not translate precisely into extra jobs - particularly as a lot of these hours are a result of a British work culture of presenteeism - the TUC is concerned persistent and excessive hours of unpaid overtime are holding back job creation.
Some employers are forcing staff to work extremely long hours that damage their health, when taking on extra employees would be far more productive and provide much needed jobs, says the TUC.
Workers in London (26.9%) and the South East (25%) are still the most likely to work unpaid overtime. Workers in the West Midlands (up 3 per cent) and the North East (up 2.2%) have experienced the sharpest rise in the likelihood of working unpaid overtime over the last year, according to the TUC analysis.
The number of workers doing unpaid overtime has increased by more than a million since records began in 1992, when 4.2 million people regularly did unpaid overtime, to 5.3 million people in 2011. The proportion of workers doing unpaid overtime has also increased slightly, from 19.7% in 1992 to 21.1% in 2011.
TUC general secretary Brendan Barber said: "The heroic amount of extra unpaid hours put in by millions of workers make a vital - but often unsung - contribution to the UK economy.
"While many politicians and financial institutions have spectacularly failed to do their bit to help the UK economy, millions of hard-working staff clearly have and we hope employers congratulate them for their efforts on Work Your Proper Hours Day this year.
"But while many of the extra unpaid hours worked could easily be reduced by changing work practices and ending the UK's culture of pointless presenteeism, a small number of employers are exploiting staff by regularly forcing them to do excessive amounts of extra work for no extra pay.
"This attitude is not only bad for workers' health, it's bad for the economy too as it reduces productivity and holds back job creation.
"No-one wants to see us to become a nation of clock-watchers. But a more sensible and grown up attitude to working time could cut out needless unpaid hours and help more people into work."
