The Trades Union Congress (TUC) claim that workers are doing themselves out of pay; on average, employees who work unpaid overtime should earn £4,650 for hours worked over and above their contracted obligations.
This is equivalent to working for free until 25 February.
The unpaid work amassed to a total worth of £23 billion in 2004.
The TUC have declared 25 February 2005 ‘Work Your Proper Hours Day’.
Union General Secretary, Brendan Barber said: “We’re not saying that we should turn into a nation of clock-watchers. Most people do not mind putting in some extra time when there’s a crisis or an unexpected rush. But too many workplaces have come to depend on very long hours. They get taken for granted and staff have to do even more if there is an unexpected rush.
"Worst of all is that many long hours workplaces are inefficient and unproductive. People are putting in long hours to make up for poor organisation and planning in the workplace.”
The findings, say Barber, put employer complaints of the cost of benefits including pensions and time off for working parents in a new light:
“Employers have been cutting back on pensions even as their staff put in longer hours.”
Workers in the Capital were found to work the longest hours. Unpaid overtime totalled 7 hours 54 minutes a week.
If paid for these hours workers would have accrued an extra £7000 a year, say the TUC.
Londoners were followed by employees in Wales at 7 hours 42 minutes (worth £4,320) and those in the West Midlands at 7 hours 36 minutes (worth £4,410).
The figures have been analysed from official National Office of Statistics employment data.