Take a collection of jeans out of any woman’s closet and you’ll likely find an array of sizes that all fit identically — why?

That was the question on one Long Islander’s mind when she recently asked her 10,000 TikTok followers why men’s pants are categorized by two size numbers — the waist and inseam lengths — while women’s have “one number that correlates to absolutely nothing.”

“Why do i have 3 different sizes of jeans in my closet that all fit me perfectly???” the content creator, Jess Jaeger, wrote in the caption of her viral TikTok clip.

And it seems like she isn’t alone in her bewilderment — hundreds of commenters lamented the drastic variation in jean sizing for women.

“My pants range from size 00-8,” one person wrote.

“And they’re never the same at different stores! A 14 at one store could fit like a 12 in another store!!” griped another.

“There’s zero consistency too, how am I a size 26 and a size 30 at the same time,” complained someone else.

The phenomenon could be chalked up to “vanity sizing” — the number on the tag is a size or two smaller than what you would actually wear, supposedly boosting the customer’s self-esteem.

“What’s happened over time is that (brands) have evolved their sizing to represent who they believe their core customer is,” Jessica Murphy, co-founder of the shopping platform True Fit, previously told Today.

“That’s why we have so much inconsistency. If you have a brand catering to a 60-year-old customer, their size medium is going to be representative of their demographic,” she added. “If you contrast that with a brand serving a tween or teenage customer, their size medium is going to look very different.”

Vanity sizing can result in a “difference in actual waist size, [which] can vary from half an inch or higher,” Joseph Pastrana, a men’s fashion expert and author, told the Daily Mail this week.

Overall, sizing is “complicated,” he said. For men’s pants, sizing is measured by the ratio of inseam to waist circumference, although how exactly it is calculated has been “lost in time.”

“To make matters worse, as they years have gone by, they’ve adjusted what that number means to anything from half an inch to an inch and a half difference,” Pastrana continued.