There has been a £5.4 billion shortfall in school budgets over the past three years, according to a group of unions.
The School Cuts coalition said 91 per cent of schools in England have been affected.
Quick read: No new money for schools in Spring Statement
The coalition includes the Association of School and College Leaders (ASCL), GMB, the NAHT headteachers’ union, the NEU teaching union, Unison and Unite.
They said that their latest analysis represented the most comprehensive examination of school funding figures, bringing together the schools block allocation, the pupil premium and sixth-form funding.
According to the coalition, these funding streams have failed to keep pace with school costs, leaving schools with a shortfall of £5.4 billion.
The new analysis comes after previous figures published by the group were criticised as “misleading” by Sir David Norgrove, the chair of the UK Statistics Authority.
Geoff Barton, general secretary of ASCL, said: “Schools across the country have had to make severe cuts and there are more on the way as reserves are drained and deficits increase.”
Paul Whiteman, general secretary of the NAHT, said: “School budgets are at absolute breaking point. School leaders have made all the obvious savings.
“Now, class sizes are rising and the range of subjects schools can offer is shrinking as they desperately try to balance the books. Everyone agrees that the school funding crisis can only be solved by new money from the Treasury.”
And Kevin Courtney, joint general secretary of NEU, said: “This is an intolerable situation. Children and young people are being short-changed by a government that believes education can be run on a shoestring. This situation cannot go on.”
The DfE continued to maintain that the analysis was "misleading".
A spokesperson said: “While we recognise that schools have faced budgeting challenges, this government has prioritised school funding, while taking difficult decisions in other areas of public spending – protecting the schools budget overall for 5 to 16 year olds in real terms since 2010.
"School funding in England is at its highest ever level and since 2017 we have given every local authority in England more money for every pupil in every school.
“Standards in our schools are rising; the attainment gap between disadvantaged students and their more affluent peers has narrowed since 2011; the proportion of pupils in good or outstanding schools has increased since 2010; and our primary school children have achieved their highest ever score on international reading tests.
“The secretary of state has made clear that as we approach the next spending review, he will back head teachers to have the resources they need to deliver a world class education.”