The proposals include a pledge to allocate £2.7 billion of capital investment over the next parliament to ensure that places exist to meet demand.
The party says it will transition to a new supply-side funding model with direct Government subsidy.
By 2020 Labour would extend the 30 hours to all parents of three- and four-year-olds, not just those in work, which it says would benefit an extra 626,739 extra children, on top of the 390,000 who would currently qualify.
It would also extend the two-year-old 15-hour offer to all twos, which it says would benefit 409,578 extra children, by 2021.
Labour says that it estimates that its plans would cost an extra £5bn a year by the end of the parliament.
The party has also pledged £500m to reverse cuts to children’s centres.
Figures show that there are now more than 1,240 fewer designated Sure Start children’s centres – a fall of around 34 per cent since 2010.
The numbers are based on Department for Education statistics from 2010 and local authority responses to Freedom of Information requests received between January and March 2017.
Labour has also pledged to phase in subsidised provision on top of funded entitlements, to ensure parents have access to affordable childcare, whatever their working pattern.
There will also be a move to providing some childcare for one-year-olds and extend maternity leave to 12 months in the longer term.
The party has also said it wants a transition to a graduate-led workforce by increasing staff wages and training.
Labour leader Jeremy Corbyn appeared on BBC Radio 4’s Woman’s Hour to talk about the childcare plans, telling interviewer Emma Barnett, ‘It’s not just a women’s issue. It affects the whole community and it affects all of our children. And it’s there in our manifesto and is clearly set out.
‘Because at the moment we have a patchwork of pre-school opportunities, childcare, which means some children don’t get very much opportunity, some get more. What we want is a universal offer of 30 hours per week.’
Asked how much unmeans-tested childcare for 1.3m children would cost he said, ‘It will obviously cost a lot to do so, we accept that.’
Mr Corbyn, added, ‘The point I’m trying to make is we’re making it universal so that we’re in a position to make sure that every child gets it, and those that can at the moment get free places will continue to get them, and those that have to pay won’t and we will collect the money through taxation, mainly through corporate taxation.’
Put on the spot about how much it would cost Mr Corbyn, who Ms Barnett said was logging into an ipad, said, ‘Can I give you the exact figure in a minute please?’ adding that, ‘All of our manifesto if fully-costed and examined.'
Mr Corbyn continued, ‘I think what is important for voters to understand is that if we don’t invest in our children and we don’t invest in them for the future then they do less well in primary school, less well in secondary school, and less well in the future.’
Pressed again for the cost he said, ‘I want to give an accurate figure.’
The interviewer then said, ‘Why on earth are you giving free childcare to people who can afford it, if it’s unmeans-tested, you don’t have the figure?’
Mr Corbyn said, ‘The important thing is that all children get a chance to grow up together. At the moment we have a system which separates out in the sense that a child of wealthy parents may well be able to go to a paid-for pre-school or nursery facility, others will not get that chance because their parents can’t afford it, or if they’re poor will get a free place.
‘What we think is that it’s more important for the whole community and collect the money back through taxation on the principle of universalism, which the same applies with the National Health Service, and applies with mainstream education.’
Later asked the single policy that would improve women’s lives he said, ‘Big investment in early years education and our education strategy in schools.'
Sector organisations welcomed Labour’s plans but stressed the need to end current under-funding to make the proposals work.
Neil Leitch, chief executive of the Pre-school Learning Alliance, said, ‘Labour is quite right to state that every child, regardless of background, should have the best start in life, and we are pleased to see the early years placed so prominently on Labour’s political agenda.
‘That said, as we warned when Labour’s manifesto was announced, unless this policy is adequately funded then it simply won’t work.
‘Today’s announcement details that their plans to rollout universal childcare to all two- to four-year-olds would cost an extra £5bn per year by the end of the parliament, however if these costings are based on the current, inadequate early years funding rates, then this pledge will inevitably be underfunded.
‘Furthermore, it’s unclear whether Labour has factored future delivery cost rises into its costings. Given its manifesto promises to increase pay levels in the early years sector, and its pledge to increase the national minimum wage more generally, this is vital. Add to this the fact that staff wages make up 70 - 80 per cent of overall provider costs, and the significant increase in staffing numbers needed to support the move to a universal offer, and it’s clear that the sector’s funding needs are likely to increase significantly over the duration of the next Parliament.’
Mr Leitch also welcomed the plans to put £500,000 into Sure Start to reverse the cuts.
‘Children’s centres are a vital source of support for both children and parents, and particularly for those more vulnerable families, and yet over recent years, we have seen a consistent reduction in services due to a chronic lack of adequate funding,’ he said. ‘Regardless of who wins the election, it is vital that the next Government recognises the importance of these services and takes steps to ensure that those families who are most in need of support have access to it.’
The National Day Nurseries Association said Labour’s plan was an ‘ambitious pledge’ that would help millions of families.
Chief executive ‘Purnima Tanuku, said, ‘The right help with childcare costs will reduce the financial burden and encourage more parents into work. Research also shows that children who receive high quality early learning will have the best life chances.
‘But the current system is not working because it has been is chronically under-funded by successive governments. Until this funding crisis is addressed, plans to increase beyond what has already been promised are overly ambitious.
‘Ironically, the reason childcare fees are so high is under-funding for so-called free places. Successive governments have not put in anywhere near enough investment.
‘This underfunding has led to endemic low pay within the early years sector and consequently a recruitment crisis, with practitioners abandoning low paid positions for better paid jobs elsewhere in supermarkets, for example.
‘Any realistic pledge to increase ‘free’ childcare must be backed up by a fully-costed workforce strategy with a commitment to improve salaries above the National Living Wage and make childcare an attractive career. Nurseries will not be able to meet Labour’s pledge to raise the Minimum Wage to £10 by 2020 unless there is substantial investment to pay for increased payrolls.
‘These proposals must also have the full backing of the early years sector, which must be consulted at every step of the way to make sure the plans are deliverable.’
This afternoon Mr Corbyn apologised for not being able to give the exact figure for the cost of Labour's childcare policies in the Woman's Hour interview. Speaking at a campaign event in Watford, he said, 'I didn’t have the exact figure in front of me, so I was unable to answer that question, for which obviously I apologise. But I don’t apologise for what’s in the manifesto and I will explain exactly what the cost is.
'It’s £4.8bn it will cost by the end of the parliament and it means that 1 million children will get childcare, free childcare: 30 hours per week between the years of two and four.'