Council long-term care care services are not being received by 80% of the two million older people in need of support, a report from Independent Age and the Strategic Society Centre has found.
Of the most disabled, 70,000 do not get any form of paid or unpaid care at home.
People being supported by care workers or relatives are sometimes receiving inadequate support with 160,000 reporting their care only sometimes or hardly ever meets their needs.
The report found that older people in need of care and support were more likely to get disability benefits than receive local authority support.
The report, The Bigger Picture, analysed data from the Census, Department For Work and Pensions, the Health and Social Care Information Centre and the English Longitudinal Study on Ageing.
The aim is to help councils and providers prepare for the Care Act which comes into effect in April 2015, which will require local authorities to offer more help.
James Lloyd, director of the Strategic Society Centre, said: "This research shows the scale of the challenge facing local authorities and national policymakers, if aspirations to support older people with prevention and information contained in the Care Act are to be achieved.
"We will need a revolution in how councils, communities and families support older people who struggle with different aspects of living independently."
Mark Stoppard, head of product development at Partnership said: "Independent Age's figures clearly show that not only will councils face a high level of demand when we reach April 2015 but that many people are working hard without any meaningful assistance to support older people in the UK.
"While it is natural to want to provide help to older relatives, this can take a huge physical and emotional toll on a person so carers do need to be realistic about what they can actually do. They should also consider what support they can reasonably expect from the council and what they may need to look to the private sector for.
"With the National Audit Office warning that local authorities are not well placed financially to meet their five year ambitions, it seems that capacity issues may not be the only concern for councils as they will also struggle to fund these reforms."
