The principal is in much better shape than her school.

Principal Jazmine Santiago used school funds to install her own private gym with a bench press, pull-up bar, treadmill, elliptical machine and thigh exerciser on the third floor of PS 269 in Flatbush, sources told The Post.

When some staffers questioned the expenditure, Santiago claimed she shares the equipment with older students, according to one source.

But the underperforming school only goes through Grade 5, which would make the oldest students 11 years old and an average 4-foot-10 — not tall enough to reach some of the heavy-duty equipment.

“Their bodies are not ready for a treadmill,” one teacher said.

Staffers fumed that Santiago converted a storage room into her own private workout space in June 2014 with no consultation.

“She comes in early, she goes to the gym. Even when class is in session, she’s still in the gym,” said another teacher. Both teachers declined to give their names for fear of reprisal.

Teachers say the room is always locked and not accessible to other staff, much less students.

“No, no, the kids have their own gym,” said the teacher. “Her gym is on the third floor and it’s her own personal gym.”

Santiago, who makes $124,319 a year, refused to meet a Post reporter on school grounds and didn’t return calls.

The elementary school has struggled during her four-year reign. Only 16 percent of students passed state English tests and only 12 percent passed math exams last year.

Parents say the exercise equipment “makes no sense.”

“That’s not right at all,” said Mike Johnson, 26, who was picking up his third-grade stepson Friday.

“The funds should go to helping school issues like going toward bullying campaigns or extracurricular activities. I don’t understand how this helps.”

Department of Education spokesman Harry Hartfield said the matter would be investigated.