A Westchester 13-year-old says she was publicly “body-shamed” by school officials for wearing a sweater that barely exposed her belly button.

Now her family and hundreds of supporters are demanding in an online petition that the school change its uptight dress code.

When Samantha Wilson, an eighth grader at Irvington Middle School, got dressed on Wednesday morning, she chose her favorite top: a $20 black-and-white H&M striped sweater she had previously worn to school on several occasions, including for her yearbook photo.

But during her third-period science class, the teen was called into assistant principal Allyson Daley’s office for an alleged 30-minute dressing down about her “inappropriate” outfit, which included a pair of high-waisted leggings. A teacher had reported her to the administration.

“I was told it was a distraction to the boys, and that my midriff and bra strap were visible,” Samantha told The Post. She admitted that the boxy sweater can sometimes slip off her shoulder and reveal a bit of bra strap, but said her midriff was only visible when she raised her hand in class to answer a question.

“It felt like a personal hit on me and my clothing style,” said Samantha, who finished out the school day in an overcoat.

“I walked into my next class trying not to cry. But I lost it and I burst into tears,” she recalled of her fourth-period academic lab. “When the teacher asked why I was crying, my friend said I was dress-coded. The teacher said, ‘She deserves to be.’ He said that in front of my entire class.”

According to the most recent Irvington Middle School handbook, the dress code is meant to “help promote an environment focused on learning” and “extremely brief garments are not permitted . . . including garments in which any midriff skin is easily exposed.”

But the theater-loving “B student,” who said she has never been in trouble, can’t understand what the uproar was about.

“It’s basically just like every other sweater. I’ve worn it to auditions before, because I thought it looked nice,” said Samantha.

‘I walked into my next class trying not to cry. But I lost it and I burst into tears.’

Her 17-year-old sister, Cydney, a senior at Irvington High School, even borrowed the sweater for a college interview last fall. On Wednesday night, she launched the Change.org petition, which had 390 signatures as of Friday.

Cydney, who said she was previously “dress-coded” at the middle school for a layered camisole she was told exposed too much of her back, thinks the rules are too strict at Irvington schools. “This is definitely a long-standing problem in our district,” she said. “Some teachers need sensitivity training.”

The petition — which declares “nobody’s belly button is inappropriate” — calls for Irvington Middle to change its dress code so as not to ban bare midriffs. Online comments of support and concern include, “Treating girls this way at such a critical age of development has a lasting impact on their self-esteem well into their adulthood.”

Irvington Schools Superintendent Kristopher Harrison said in a statement, “School dress codes are never easy and we know that fashion sometimes conflicts — still, we want to get it right and we will be working with our students and stakeholders to do just that.”

Samantha and Cydney’s mom, Jamie Wilson, is hopeful they will get it right. She said of her younger daughter, “She’s a very innocent young girl. The hit [school faculty] put on her self-esteem was tremendous.”