Care home fees have increased by more than 50% over the last five years, a charity has found.
Around 40% of care home residents get no help with the cost
But Help the Aged said the basic state pension has risen by only 21.5% during the same period.
More care home fee rises are expected by the end of this month, possibly up to 25%, and the charity warns many will not be able to cope.
Its report comes as the Joseph Rowntree Foundation called for a "comprehensive overhaul" of care home funding.
At the moment, elderly people in the UK who have capital over a certain amount must pay the full cost of their care.
In England and Northern Ireland, the limit is £21,000, while in Scotland the figure is £20,000 and in Wales it is £21,500.
AVERAGE CARE HOME FEES
2000/1 - £13,936
2005/6 - £21,112
Increase - 51.5%
Help the Aged estimates this group accounts for around 40% of people entering residential or nursing homes.
The charity says the care funding system in the UK is extremely complex and there are concerns that many older people and their families are not aware of the state-funded benefits they may be entitled to which can help towards the cost of care.
Peter Fisher, of Help the Aged's care fees advice service, said: "While the government mulls over the findings of the Wanless Report which highlighted the serious lack of funding for care in this country, the real losers in the meantime are the thousands of older people who are grappling first-hand with this daunting reality now.
2000/01 - Average - £6,295. Shortfall - £7,641
2005/6 - Average - £7,418. Shortfall - £13,694
"Every year we're seeing inflation-busting increases in care home fees while meagre rises in the basic state pension fail to even vaguely keep pace."
He added: "For older people, the task of raising the money to meet the cost of their care is therefore becoming increasingly complicated and challenging.
"The situation is compounded by the fact that we now have a far greater number of older people who are living longer and who exceed the means-test limit because they own their own home.
"Thousands of older people each year have no choice but to sell their home to pay for their care.
"But it's frightening how quickly even the considerable amount of money raised in that way can diminish."
Help the Aged's data was published as the Joseph Rowntree Foundation called for a reform of the care-home funding system.
A report from the think-tank called the current arrangements "inequitable and incoherent".
It suggested a range of measures including creating a voluntary scheme allowing homeowners to access capital tied up in their property to pay for home-based care; doubling the capital threshold for those in care homes after selling their properties and doubling the personal expenses allowance for people supported by local authorities in care homes.
Sir Christopher Kelly, a former senior civil servant at the Department of Health who advised the report's authors, said: "If we continue with this already over-stretched, inequitable and incomprehensible system of funding while demand continues to rise, there will be serious costs for the dignity and well-being of older people.
"In the longer term, a comprehensive overhaul is needed but immediate changes could address the most problematic elements of the current system."