Almost 190,000 new care home places will be needed in under two decades to accommodate soaring demand, experts have predicted.
The number of people aged 65 years or older who will need care home places will rise by 85.7% by 2035 - with 189,043 additional places needed, according to a new study published in The Lancet.
And by 2025, an additional 71,215 care home places will be needed compared with today, experts estimate.
Increases in life expectancy have coincided with rises in the number of years that older adults spend with substantial care needs, the authors found.
For adults over 65, the number of years spent with substantial care needs nearly doubled between 1991 and 2011, according to the study.
Researchers compared data from two studies, each with more than 7,500 participants aged 65 and older from Cambridgeshire, Newcastle and Nottingham, which were conducted two decades apart.
Between 1991 and 2011, life expectancy increased for both men and women.
And the proportion of years living with low, medium or high dependency increased.
For the purposes of the study, those with a low level of dependency were classed as such if they needed help less than once a day with tasks such as washing, shopping and housework; those with medium dependency needed care at regular times each day and those with high dependency needed round-the-clock care.
The authors found that for adults over 65, the number of years spent with substantial care needs, classed as medium or high dependency, nearly doubled between 1991 and 2011 - rising from 1.1 years to 2.4 years for men, and from 1.6 years to 3.0 years for women.
The researchers also analysed whether or not people lived in care homes or the community.
They found that older people with substantial care needs were less likely to be living in a care home in 2011 than in 1991.
For example, the percentage of adults aged 85 who required 24-hour care who were living in a care home fell from 73.5% to 51.8% over the period studied.
The authors projected that if rates of dependency remain constant, there will be an additional 190,000 older people with medium dependency, and 163,000 with high dependency by 2025 compared with 2015.
This means that by 2025, 883,000 people will have medium dependency and 813,000 will have high dependency.
Assuming that the proportion of those with medium and high dependency who are in care homes remains constant, these increases will require a further 71,215 care home places by 2025 and 189,043 by 2035, the authors wrote.
Meanwhile, the numbers of people with low dependency needs are also expected to soar to 4.44 million by 2025.
This will have "considerable implications" on families who provide much of this unpaid care, the authors said.
Professor Carol Jagger, lead author from Newcastle University, said: "The past 20 years have seen continued gains in life expectancy, but not all of these years have been healthy years.
"Our study suggests that older people today are spending more of their remaining life with care needs.
"Though most of the extra years are spent with low dependency - including help with activities such as washing, shopping or doing household tasks - older men and women are spending around one year more requiring 24-hour care.
"This finding, along with the increasing number of older adults with higher rates of illness and disability, is contributing to the current social care crisis."
In a linked editorial, Sir Andrew Dilnot - who chaired a government review on the funding of care and support - said the projections "demand attention and action".
Sir Andrew, from the University of Oxford, added: "Expenditure on the care of older people will need to increase substantially and quickly.
"It will be important to ensure that this expenditure is managed efficiently, and in particular that the boundary between health care and social care is well handled."
Commenting on the study, Janet Morrison, chief executive at the charity Independent Age, said: "Creating over 70,000 new care home places seems to be a tall order for a care sector commonly recognised to be in crisis.
"Older people and their families really can't wait much longer to see a long-term solution to the crisis in adult social care."
Rob Burley, director of policy at Alzheimer's Society, said: "The Government and sector as a whole must act now to ensure we have future-proof plans to accommodate the enormous rise in demand.
"A new approach that recognises the needs of people with dementia is desperately needed."
A Department of Health spokesman said: "High quality care isn't just about care home beds - 61% of people are cared for in their own home and since 2010 there has been a growth in home care agencies of more than 2,900.
"We've given local authorities in England an extra £2 billion boost over the next three years to maintain access for our growing ageing population and to put the social care sector on a sustainable footing for the future."