The number of academies is likely to triple in September if the Conservatives win power and could increase tenfold, immediately transforming England's schools system, a TES analysis suggests.
The party has said it will automatically pre-approve all schools rated "outstanding" by Ofsted for academy status.
The TES research - in which a sample of heads from every region in England was interviewed - indicates that more than 500 schools would accept the offer and opt out of the state system next term, while around 1,500 more would consider it.
It could mean as many as one in ten state-funded schools leaving national teacher pay deals, the national curriculum, and local authority support and control.
Teaching unions warn it would create "absolute chaos", division and a "free for all".
They say schools considering the change should first think about the full implications for themselves and the system as a whole.
But shadow schools secretary Michael Gove was "delighted" that so many schools wanted to take up the offer. "Unlike the Government we believe that headteachers, not bureaucrats, should be running schools," he said.
The Tories plan to make a vast increase in the number of academies from the current 203, and their most direct and quickest method will be pre- approval for outstanding schools.
The latest Ofsted figures show that 14 per cent of primaries have the top inspection rating and 19 per cent of secondaries.
More than a quarter of the secondary heads questioned in the research (26 per cent) said their schools would accept academy status, and another 41 per cent said they would consider it.
Of the primary heads, 16 per cent said their schools would become academies and another 53 per cent said they would consider the status.
But around a third of heads from both sectors said their outstanding schools would reject it.
Chris Keates, general secretary of the NASUWT union, said: "What we are witnessing is the break-up of state education. The national pay and conditions framework will go out of the window.
"We will be watching the weakest schools go to the wall and the staff and pupils in them left languishing."
Freedom, empowerment and the ability to set their own curriculum were all cited as incentives by heads of outstanding schools.
But others feared that Ofsted verdicts were not a reliable basis for it and that some schools would be too small to work as academies.
John Bangs, NUT head of education, said: "It would be absolute chaos, particularly among primaries."
David Laws, Liberal Democrat schools spokesman, said it showed how superficial the Tories' policy is. "The Conservatives think that all you need to transform schools is to rebrand them," he said.
The Labour party declined to comment.
Additional reporting by John Elmes and Shade Lapite.
Original paper headline: Academy numbers would triple in September under Tories