The amount of unpaid overtime Australians work is again in the spotlight, with a new survey revealing four in five overtime workers want to work fewer hours.

The research, commissioned by the Australia Institute, found half of all workers surveyed would like a shorter working week.

In fact, they said they would like to cut, on average, two-and-a-half hours from their weekly grind.

The executive director of the Australia Institute, Richard Dennis, argues cutting back on overtime could create about 400,000 extra jobs in Australia and improve the health of workers.

"If you could convert all of the unpaid overtime into new jobs you could create more than 1 million new jobs," he said.

"But we've estimated that if the number of hours reduced were apportioned in the same way that occurred when France reduced their hours you could create 390,000 new jobs."

Dr Dennis says people working 50 hours or more each week would happily slash 13-and-a-half hours from their workload.

"Australian workers are donating more than $70 billion a year to their employers in terms of unpaid overtime and that's a very generous gift, and our employers have taken, got into the habit of accepting it," Dr Dennis said.

"But the reality is, if you don't know how many hours you work, you can't really figure out what your hourly rate of pay is.

"Full-time workers want to work a lot less and part-time and casual workers want to work a lot more, so the labour market really isn't matching the preferences of employers and the preferences of employees," he said.

Dr Dennis says Australia's overwork culture is counter-productive.

"We're saying to people we want them to tackle lifestyle illness like diet through fixing their diet, fixing their exercise and seeing their doctor before they get sick," he said.

"But what our survey respondents are telling us is that they're too busy to cook home-cooked meals, they don't have time to exercise and, in fact, when they're sick they're more likely to soldier on and go to work than they are to go to the doctor and find out what's wrong."

Dr Dennis says tackling the problem will require action on a number of fronts.

He wants governments to introduce caps on working hours, employers to cut their reliance on unpaid overtime and workers to pay more attention to how much of their time they are giving away.