Mayor Zohran Mamdani crowed Friday that New York City now complies with the state’s mandate to reduce public school class sizes — but it only happened after he begged for an extension and his administration tweaked the math.

Hizzoner and Schools Chancellor Kamar Samuels announced that 73.4% of Big Apple public school classes now comply with the class-size law, “surpassing” the 70% compliance target for the 2026-27 school year. 

The law requires all New York City classrooms to have no more than 20 to 25 students, depending on grade level, by the 2029–30 school year.

The limits are set at 20 students for K-3rd grade, 23 for grades 4 to 8 and 25 for high school.

The Mamdani administration successfully pushed for a two-year extension after Samuels admitted in March that the mandate would be “very difficult” to meet by the 2027–28 school year.

The state also reduced the compliance target this year to 70%, down from the original target of 80%.

In addition to the decreased target and extension, which weren’t mentioned in City Hall’s self-congratulatory press release, the city also quietly changed its math to hit compliance.

On page seven of the Department of Education’s report, it admits that this year’s count included “cluster” classes — like gym, music or tech classes that aren’t taught by their usual teacher.

“NYCPS updated its data reporting capabilities and infrastructure to include cluster classes to further support compliance with the law,” the November report states.

Without the tricky tweak, the Big Apple would have only hit a 69.5% compliance rate under previous years’ counts, Samuels told Chalkbeat, which first reported the news.

The report also states that exam prep courses at the middle and high school level were added into this year’s count.

Meanwhile, despite Hizzoner’s administration bragging about its $244 million investment to hire teachers to comply with state law, the Big Apple has 500 fewer teachers than last year’s total of 69,900.

Enrollment in New York City public schools plummeted by nearly 22,000 last year alone in its steepest decline since the pandemic, according to an October Comptroller report.

The Big Apple has lost a whopping 187,000 students since the 2013-14 school year, the comptroller report also found.

City Hall and the NYC Department of Education did not respond to requests for comment.