Millions of people who are pinning their hopes on funding their retirement by moving into a smaller property risk their downsizing dream becoming a nightmare, a report warns.
As many as three million working age Britons plan to use the value of their home to fund their later years.
The idea is to downsize to a smaller home when they retire and free up some cash, according to the report, written by former pensions minister Steve Webb, who is now director of policy at Royal London.
But while some may believe that house prices are a one way bet, Mr Webb warned that relying just on the value of your home to fund your retirement is an "incredibly risky strategy".
The report said: "For too many people, the 'downsizing dream' could turn out to be a nightmare."
The report, titled the Downsizing Delusion, estimated the income that people who downsize may expect to generate from swapping an average detached home for a typical semi-detached property.
A typical detached home is worth around £310,000, while buyers can expect to pay around £197,000 for a semi-detached house - meaning someone may expect to raise a pot of around £113,000 from downsizing.
Someone using this cash to buy a retirement income called an annuity may end up with an annual income of around £13,700, made up of their annuity income and the full state pension, the report found.
But the typical worker earns £27,400 a year - so an income of £13,700 would mean their income had halved on retirement. For most people, this would be an unacceptable slump in living standards, the report said.
Mr Webb said: "Hoping to live off the value of your home could be a downsizing delusion for millions of people."
He continued: "Even with today's record house prices, very few people could fund a retirement by selling up and moving to a smaller property.
"In addition, house prices can be volatile, not least in the light of the recent Brexit vote, and depending on the value of a single asset - your home - to fund your whole retirement is an incredibly risky strategy."
Earlier this week, the Royal Institution of Chartered Surveyors (Rics) said expectations for house price growth in the coming year had been reined back significantly in the wake of the vote to leave the EU.
The Royal London report made some assumptions that were on the generous side for someone planning to use the downsizing strategy to fund their retirement.
So, in reality, people may end up with a much smaller retirement income than the calculations.
For example, the study did not factor in the fees that someone would have to pay for buying and selling such as stamp duty, which would eat a particularly big chunk out of any equity released in London, where house prices are generally higher.
The figures were also based on average wages, whereas many people tend to earn more later in their career, so the income shock after retiring could be bigger than the calculations.
And with many people retiring as a couple, two people could be relying on the proceeds from downsizing one home to fund their retirement.
Looking across the UK, the report found that trading down from the average detached house to the average semi-detached house at retirement would generate less than two-thirds of pre-retirement income everywhere outside London.
But in London, the calculation was particularly generous to downsizers. It was assumed that someone on an average London wage can afford a detached home, typically worth £854,000, whereas in reality many will not be living in this type of property.
The report also warned other hurdles may cause those with dreams of downsizing to stumble. Many of those heading towards retirement age are still housing adult children who cannot afford to get on the property ladder themselves.
There is also a growing trend for people taking out mortgage deals lasting beyond the age of 65 - so some people may still be paying off their home loan by the time they want to retire.
The report used research from the Council of Mortgage Lenders (CML), Land Registry figures and Office for National Statistics (ONS) wages figures for the findings, as well as a Baring Asset Management report which found that around one in 12 (8%) people - equating to three million across Britain - plan to sell their main home to fund their retirement.