Clegg believes changes to working practices will encourage more women back into employment.
In a keynote speech in London tomorrow, he will encourage a culture in which people feel confident to ask employers to change their working hours.
The Right to Request scheme, which only applies to those with children under 17, relatives and some carers, would allow everyone to ask their employer for flexible hours if they wish to help others with childcare.
Employers would be forced to consider all requests 'in a reasonable way'. Clegg believes new legislation, expected by 2014, would "drive a culture shift in the workplace", to fit a modern economy.
Clegg will say: "If we had the same proportion of female entrepreneurs as the US, then the economy would be better off by £42 billion."
He will also say: "While women in this country are now better qualified than men and more girls go to university, they lag behind in the workplace. That requires sweeping away the clapped-out rules that make no sense for modern families."
UK work-life balance organisation, Working Families, has supported the reforms and believes it will be "good for business".
Sarah Jackson, chief executive of Working Families, said: "Many businesses already offer the right to all employees because it leads to performance gains.
"The Government's own assessment shows the extension will bring a net benefit of £222.5 million to employers through increased productivity and through savings from reduced sickness, absenteeism and recruitment costs. Flexible working is an essential tool for business success."
Jackson added: "Families too will benefit when more workplaces adopt flexible working as the norm. There has been great progress since the introduction of flexible working rights, but in many areas there is a reality gap between good intentions and the facts of family life.
"There could not be a better time to boost the UK's performance by changing the way we work to enable all employees to perform at their best. What we need from the Government is a consistent positive message about the value of flexible working to promoting economic growth."
