Parents propped up school budgets to the tune of pound;68.5 million in the past year, new figures show.
They have paid for computers and software, sporting equipment and subsidised trips for thousands of pupils.
A report from the National Confederation of Parent Teacher Associations found PTAs are playing an increasingly vital role in keeping schools in the black.
An average of pound;5,400 was raised per school in the past year.
But some parents collected much more, raising huge sums for essential projects. At Sandgate school in Kendal, Cumbria, pound;160,000 was raised to renovate a playground for pupils with severe learning and physical difficulties.
David Butler, NCPTA's chief executive, said: "We knew PTAs made a real difference... but even I am amazed by how much the Family and Friends of Sandgate raised.
"PTAs provide a valuable and increasingly vital source of funding for schools. pound;68.5 million is a fantastic contribution to the costs of educating our children."
He said that PTAs were also involved in other ways, such as promoting home school partnerships and helping parents to get actively involved in improving their children's education.
Campaigners at Sandgate embarked on sponsored head shaving, parachute jumps and a Land's End to John O'Groats bike ride. Lynn Perchard, whose son Jonathan, 14, is a pupil at Sandgate, said: "We just started off with a friend lending us some books about funding bodies and it took off from there. People doubted that we'd be able to raise so much money, but as they realised we were serious, more came on board."
The NCPTA gives advice on fundraising. Ring 01732 748850 or see www.ncpta.org.uk