In the past two years, vacant teaching posts have increased by 24 per cent, Eteach data has shown.
In addition, the figures show nine per cent more teaching vacancies this September than the same month in 2016.
At least 300,000 pupils will be without a permanent teacher as the 2017/18 academic year starts and two-thirds of teachers are looking to leave their current role within the next three years.
Eteach has analysed teacher vacancy figures from 7,000 schools to take the temperature on the nation’s growing teacher recruitment crisis.
Data from a quarter of the UK’s schools, shows there will be almost 14,000 teacher vacancies as the school year begins.
With an average UK class size of twenty-two pupils, this leaves at least 300,000 pupils without a permanent classroom teacher this September.
Eteach surveyed over 1,800 teachers and the data reveals two-thirds are thinking of leaving their current job in the next three years. Of those, excessive workload (48 per cent) and low morale (38 per cent) were given as the most prominent reasons for planned resignations with 80 per cent of teachers taking work home with them on weekends and during holidays.
However, despite increasing pressures, over half of teachers (56 per cent) would still recommend the profession to a friend.
Paul Howells, founder and chief executive of Eteach says: “In my 20 years of working with schools on teacher recruitment I have never seen so many unfilled vacancies. Teaching is failing to attract enough graduates, and schools are struggling to hold on to their current teachers, creating a perfect storm of pressures.
“As schools start the new academic year, thousands will be scrambling for last-minute supply staff and paying agencies a premium for emergency cover during a period of tightened budgets.
“Despite the nature of the school recruitment calendar there are steps schools can take with a more proactive approach and new technology to mitigate the growing September supply crisis.”