Most of the 65,000 teachers in NSW say a chronic staff shortage has led to unmanageable workloads that makes them feel burnt out and demoralised.
NSW Teachers Federation president Angelos Gavrielatos says the unfolding crisis is putting the state's education future at risk with some 3800 teachers needed by 2027 to keep the profession afloat.
"The crisis in which we find ourselves today is worsening," he told a parliamentary inquiry into the teacher shortage on Thursday.
There were 1657 teachers vacancies across the state as of June, he said.
"The government has failed the students of NSW," Mr Gavrielatos said.
"Thousands of students every day ... are being denied their right to learning. They're being denied their future."
The probe comes a little over a month after thousands of NSW public and Catholic school teachers walked off the job demanding better pay and conditions.
The unions want a pay rise of five to seven per cent to stem the flow of teachers abandoning the job. The NSW government has offered a pay increase of three per cent.
Education Minister Sarah Mitchell previously defended the government's public sector wages policy, calling it the most generous in the country.
Mr Gavrielatos said fundamental change was needed to address cumbersome, administration-focused workloads, with primary school teachers only given two hours a week to prepare classes - a figure that hadn't changed since the 1980s.
An online survey commissioned by the committee found over 92 per cent of respondents wanted to see a reduction in the administration workload for teachers.
Of the nearly 11,300 teachers and administrators surveyed in NSW, about 60 per cent said they would leave the profession in the next five years.
Inquiry committee member and Labor MP Courtney Houssos said deeply entrenched problems in the education sector were affecting the futures of schoolchildren.
"After 12 years of this NSW Liberal-National Government, we have the fastest-falling education outcomes in the world," she said.
"Yet the NSW government is failing to even acknowledge the chronic teacher shortages that are plaguing our schools."
A Monash University report published in June found more than half of Australian primary and secondary school teachers surveyed were planning to quit the profession, with some describing their workload as excessive and unsustainable.
Fiona Longmuir, one of the report's researchers, told the inquiry the key message was that the workload for teachers was unsustainable and they felt they were forced to document every decision they made.
"The working conditions are difficult. It's having impacts on their health and wellbeing, their mental health, their family life," she added.
Dr Longmuir said teachers also felt they were being undervalued in public policy debates.
"It's exacerbated by being demoralised by public policy and media messages that ... essentially bash teachers when there's crises in education," she said.
Newcastle University professor Jenny Gore said too many teachers were "burnt out, exhausted, overwhelmed and demoralised".
While teaching ranks highly as a preferred career path for many high school students - including high-achieving ones - it falls out of favour once students enter university.
Prof Gore said more government resources should be invested in training graduates, who were often unprepared for the demanding reality of the profession.
"If we want to slow the attrition (rate) from the profession, and we must, then investing in initiatives with clear evidence and positive effects for teachers and students is critical," she said.
