The amount of time spent needing daily care in late life has doubled in England over the past two decades, a study suggests.
The Newcastle University study found men spent 2.4 years on average needing regular care and women three years.
This includes everything from help with washing and dressing each day to round-the-clock care.
Researchers said it suggested there needed to be a sharp increase in the number of care home places to cope.
It comes as ministers consider a new way to fund the system.
The government has promised major reform amid reports that councils are struggling to provide enough support to cope with the ageing population.
The latest research, published in the Lancet, looked at not just the growth in the numbers of older people but also how many of those years were spent needing daily care.
Between 1991 and 2011, life expectancy increased by more than four years for both men and women to 82.6 and 85.6 respectively.
But the number of those years spent with substantial care needs rose much more rapidly, from 1.1 to 2.4 for men and 1.6 to three for women.
Looking ahead to 2025, it means there will be another 350,000 people with high care needs, the researchers predicted.
Not all of those will need to be in care homes, but the researchers said the number of places would still need to rise by a third to cope.
Sir Andrew Dilnot, from Oxford University, who has advised the government on social care, said the findings suggested spending on older people would need to "increase substantially and quickly".
Janet Morrison, chief executive of the charity Independent Age, added: "This report is further evidence, if it were needed, that the government must act urgently to put in place a sustainable social care system that is able to meet the demands of an ageing population."