School governors have pointed to a "catastrophic" squeeze on budgets, as the government prepares to introduce a new funding formula for schools.
A snapshot survey of 4,000 governors by the BBC sheds light on the existing funding pressure in England's schools.
National Governors Association head Emma Knights does however back the principle of the new funding formula.
Ministers say schools are funded at record levels and that the budgets rethink will end inconsistencies.
But the dramatic impact on already stretched budgets - even before the funding formula kicks in - has left ministers under pressure from Conservative backbenchers and head teachers in all areas of England.
The National Audit Office says schools face £3bn shortfall by 2019-20.
It comes a day after heads from 3,000 schools in England wrote to their local MPs and ministers calling for a rethink of the plans.
The difficulties being faced by schools across England were spelled out by the governors who responded to the BBC questionnaire.
"Diabolical", "devastating" and "catastrophic" were among the words used to describe prospects for schools.
Some governors described their "desperate" attempts at fundraising to fill gaps, while others explained that many subjects were being lost, particularly at sixth form level.
In Halifax, one governor said they were considering shortening the school day.
In other areas, efforts to raise extra cash included selling off school land, letting out facilities and raising sponsorship from local businesses.
One governor said their school was holding a music festival to raise cash to help with the running of the schools.
"We are just about holding things together. If it wasn't for the changes in the funding formula we would be making teaching assistants redundant," said the governor of a Warwickshire school
"We will provide a very vanilla curriculum," said a governor from Ipswich worried about the number of subjects being cut.
A Norwich governor talked of "a potentially devastating impact on behaviour support, family liaison and mental health support.
But many felt too limited to ask parents for donations: "We are in a deprived area - many of our parents are using food banks," said one governor from Blackburn.
The new formula seeks to shift resources from more highly funded urban areas to less well funded rural ones.
But there is also extra funding for schools with high numbers of children with low prior attainment.
'Winners and losers'
Speaking as the consultation period on the plan closes, Ms Knights said "everybody pretty much agrees that the principle of the formula is right".
But the lack of money in the education system overall meant some schools that had expected to gain under the new funding formula would in fact lose, she said.
"People do understand that the current system can't be defended and we do need a way of making sure we are distributing money across the country fairly."
But Ms Knights said the new formula had shown up a shortfall "in the basic building block to educate a child", which she said was a different issue.
"That's about the amount of money we need rather than how we distribute it across the country."
Her comments coincide with a separate report from the Institute for Fiscal Studies (IFS) that calls the proposals "broadly sensible" but warned of "significant winners and losers" with some schools facing "protracted cuts".
"Implementing this reform at a time when there is already considerable pressure on school budgets will inevitably be difficult," the IFS warns.
The underlying financial problems faced by state schools in England were highlighted in a National Audit Office report in December last year.
The spending watchdog said schools would have to find £3bn in savings by 2019-20, amounting to budget cuts of 8%.
The funding formula was announced in the same month by Education Secretary Justine Greening.
The government says its plan includes protections until 2019-20 to ensure that no schools will lose more than 6% of their budgets in real terms, but the IFS says these safeguards will need to remain for longer.
The Nasuwt teaching union says it has raised concerns with the DfE that claims about future school funding levels.
This had led to some schools to ask parents to make unjustified and discriminatory financial contributions to school funds, whilst also planning to cut the jobs of teachers and support staff, it said.
The union called on the Education Secretary to act to "end panic in the system", and ensure that all schools act appropriately in ensuring pupils' educational entitlement are met fully.