Ontario's fiscal watchdog says the provincial government's decision to increase class sizes will result in approximately 10,000 fewer teachers in schools over the next five years.
The Financial Accountability Officer says move will save the province about $2.8 billion over the same period of time.
The Progressive Conservative government has said the cuts were necessary to fight a $7.4-billion deficit and will result in 3,475 fewer teachers in the system over four years.
The FAO says the government arrived at that estimate by looking at the actual number of teachers in 2018-2019 that won't exist four years from now.
The financial watchdog, meanwhile, looked at the number of teachers that would have been required had class sizes not changed and factored in increased enrolment.
Earlier this year the government ordered school boards to start increasing class sizes, moving to an average for high school from 22 to 28 over four years.