Jobs have so far gone through a combination of natural wastage and redundancy following budget cuts.
And a third of the 200 schools responding to the survey said they expected to make more staff cuts from April - a further quarter were uncertain of their ability to avoid making deeper cuts.
The bulk of the returns - some 76 per cent - were from foundation schools; 44 or 22 per cent were from aided schools.
The largest number of returns were from schools in Essex and Kent, where the former GM schools had a big presence.
The survey was conducted jointly by the Foundation and Voluntary Aided Schools' Association and the Association of Heads of Foundation and Aided chools. Lawrence Upton, vice-chairman of FAVASA, said: "We always knew that GM school funding levels would be hit by the changes in the funding regime but the scale of the reductions is truly alarming.
"Taking the projected job losses alone, we estimate that more than pound;30 million at least has disappeared from school budgets in the last year. Where has it gone?"
Bob Lloyd, AHFAS chairman, added: "Teachers' jobs are being lost while local authorities take on a growing army of administrators and advisers."
Many heads said they had minimised the impact of budget shortfalls by drawing on reserves - on average pound;59,000 per school - but only half expected to do so next year.
One head said: "The past nine months have been the worst of my career." Another added: "It's like having gone back 15 years in a time warp."
However, overall schools' relationships with their local authorities appeared to be positive.