A report on school overcrowding released on Friday said the city continues to underestimate the actual need for new classroom seats.

The report, by the group Class Size Matters, says high schools in Queens and Staten Island, plus elementary schools in 11 districts, were above 100 percent utilization which means they are over full capacity.

And the crowding problem is going to get worse: an additional 60,000-70,000 additional students are expected to enroll in the New York City school system over the next decade while the new five-year capital plan would build at most 38,654 seats. 

"The situation has become especially critical at the elementary school level, and will likely become even more pronounced as pre-kindergarten programs are expanded," the authors stated.

Already, it says overcrowding has contributed to "sharp increases in class size," with class sizes in grades kindergarten to third the largest in 15 years. It says schools have lost cluster rooms that were used for science, art and other subjects, as well as spaces like gymnasiums and libraries, with more kids eating lunch at earlier hours in order to divvy up cafeteria time.

“We are tackling the serious issue of overcrowding head on," Department of Education spokesman Harry Hartfield said. "which is why we have proposed $4.4 billion dollars to open nearly 40,000 new seats, many in historically overcrowded districts, in addition to creating a school space working group that is engaging across city agencies and with community leaders to recommend long-term solutions and alleviate the problem.”

At a City Council hearing this week, Deputy Chancellor Kathleen Grimm said the city is moving ahead with plans to revise its formula for determining school space and she added that no more co-locations would be approved "unless they come from the community."

The advocacy group Make the Road New York praised the city for planning to build 2,376 new seats in Corona and Elmhurst, Queens, which it called "the epicenter of overcrowding."