An increase in the number of care home places will be needed in the next 20 years because of the rising numbers of over-85s, academics have warned.
Experts say in 2010 there were 2.6 million people aged over 80 and by 2030 it is expected to rise to 4.8 million.
This will require an 82% increase in the number of care home places, about 630,000 extra spaces, by 2030.
The study was carried out by Newcastle University's Institute for Ageing and Health.
It found that 41% of over-85s questioned never had help and a further 39% were supported to live independently.
But that meant one in five people aged over 85 needed either regular help or critical 24-hour care.
The findings, published in the BMC Geriatrics journal, indicated an increase in the older age group would place more pressure on care services.
Professor John Bond, Professor of Social Gerontology and Health Services Research, said: "We have found that 80% of people in this age group need little or no care, which is great news.
"But on the other hand there needs to be some major investment to ensure that those who need help can access the care they need."
Interviewers spoke to 841 Tyneside people born in 1921 and asked them about their ability to perform everyday tasks such as cooking, dressing and washing to measure their self-sufficiency.
Researchers then rated them on a scale according to how frequently they needed help from another person.
Carol Jagger, AXA Professor of Epidemiology of Ageing at Newcastle University said the results were "surprising" and added: "More people than we imagined can look after themselves to a large extent, which is encouraging."