Rough sleeping across Britain is predicted to jump by three quarters (76%) over the next decade, a national charity for homeless people has warned.
Around 9,100 people were sleeping rough in 2016, with the number forecast to rise to 16,000 in 2026, a new report from Crisis has suggested.
The analysis carried out for Crisis by Heriot-Watt University found that in 2016, 159,900 households estimated at almost a quarter of a million people (236,000) were experiencing a form of homelessness.
It warned that without action the most acute forms of homelessness were likely to keep climbing, with overall numbers forecast to rise by more than a quarter (26.5%) over the next 10 years to 202,200 in 2026.
The scale of homelessness had "increased significantly" (33%) across Britain in the last five years, up from 119,900 in 2011.
Jon Sparkes, Crisis chief executive, said there was a need to "first understand the scale of the problem" as the charity marked its 50th anniversary.
The report, entitled Homelessness Projections: Core Homelessness In Great Britain, stated: "If current policies continue unchanged, the most acute forms of homelessness are likely to keep rising, with overall numbers estimated to rise by more than a quarter in the coming decade and two and a half times by 2041."
It revealed that last year 68,300 households were sofa surfing, 19,300 households were living in unsuitable temporary accommodation and 37,200 households were living in hostels.
Approximately 26,000 households were living in other circumstances in 2016, including 8,900 households sleeping in tents, cars or on public transport, 12,100 households living in squats and 5,000 households in women's refuges or winter night shelters, it said.
Households in unsuitable temporary accommodation were set to almost double, increasing 93% to 37,300 by 2026, it added.
Mr Sparkes said: "We still exist because homelessness still exists, and today's report makes it only too clear that unless we take action as a society, the problem is only going to get worse with every year that passes.
"That means more people sleeping on our streets, in doorways or bus shelters, on the sofas of friends or family, or getting by in hostels and B&Bs. In order to tackle this, we need to first understand the scale of the problem."
He welcomed the Government's pledge to tackle rough sleeping, but urged "action and long term planning to end homelessness for good".
In the wake of the findings, the charity called on the public to support its Everybody In campaign, stressing that with the right support at the right time homelessness was not inevitable.
The report argued a 60% increase in new housing could reduce levels of homelessness by 19% by 2036.
The second part of the charity's report on wider homelessness is due in the autumn.
A Department for Communities and Local Government spokesman said: "This Government is determined to help the most vulnerable in society and we're working to make sure people always have a roof over their head.
"We know this is an issue Government can't solve alone and so welcome Crisis's support for our commitment to tackle homelessness and rough sleeping.
"Alongside investing £550 million to 2020 to address the issue, we're implementing the Homelessness Reduction Act, which will require councils to provide early support to people at risk of becoming homeless.
"There's more to do and ministers will set out plans shortly."
Judith Blake, the Local Government Association's housing spokeswoman, raised the importance of council house building in tackling the issue.
She said: "Councils want to end homelessness. As we have warned, councils are housing the equivalent of an extra secondary school's worth of homeless children every month.
"For families, rising homelessness is tragic. For councils housing homeless people, it is unsustainable.
"Homelessness is everyone's business, and councils need the help of health, employment and housing partners to deliver ambitions to end it.
"In particular, councils need to be able to adapt the implementation of some welfare reforms to ensure there are housing options for people on low incomes.
"There is no substitute for a renaissance in council house building if we're to truly address the rising homelessness we face as a nation.
"For that to happen, Government needs to allow councils to borrow to invest in genuinely affordable housing and to keep all of their receipts from Right to Buy sales, so that money can be reinvested into delivering genuinely affordable homes."
Shadow housing secretary John Healey said: "It is a national scandal that in 21st-century Britain the number of people experiencing homelessness is spiralling upwards.
"These new figures are a terrible reminder of the consequences of Conservative ministers' seven years of failure on housing.
"The number of people sleeping rough fell under Labour but has risen every year under the Conservatives and has now doubled since 2010.
"This is a direct result of decisions made by Conservative ministers: a steep drop in investment for affordable homes, crude cuts to housing benefit, reduced funding for homelessness services, and a refusal to help private renters."