This formula is a hack to see if short hair is right for you as…

Committing to a bob can be daunting, but there may be a hack to know whether the chin-grazing cut is fit for your face shape.

So, you’ve been influenced by the rise of celebrities opting for the chic cut — Zendaya, Ayo Edebri, America Ferrera, Rita Ora and, most recently, Sydney Sweeney — or the onslaught of TikTokers debuting the sleek style online.

But as the cut seems to be the hottest hairstyle this spring, one content creator is sharing her tried and true formula using three household items to ensure a bob will look fab, not a flop.

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In a resurfaced video posted on TikTok, creator Amy Chang uses two pencils and a measuring tape to determine if she would look “good” on her.

First, she placed a pencil sideways underneath her chin, then she held the other pencil perpendicular. The distance from the bottom of the ear to the point of intersection will determine whether a bob will be flattering.

If the measurement is greater than 2.25 inches, longer hair is ideal for your face shape, but if it is less than 2.25 inches, a bob will “look good,” she explained.

“The angle/length of your jaw is everythinggggg,” she wrote in the comments, adding that shoulder-length hair never “looked right” on her while growing up and that her DIY measurements explained why.

At its root, a haircut is meant to accentuate facial features, experts previously told Byrdie. For instance, those with rounder faces may benefit from a lob, rather than a jaw-grazing French bob, while someone with a square or heart-shaped face can more easily rock a true bob.

“Where your haircut lies can bring out certain features,” celebrity stylist Ted Gibson told Byrdie. “If someone has a strong jaw and a bob, where that bob lies can diminish the strong jaw or can highlight it.” 

But the shorter the hair, the higher the maintenance.

NYC hair stylist Sky Kim recommends that clients with short hair should head to the salon every four to six weeks for a trim to keep the bob looking fresh — and even more frequently if fringe is involved.

However, Canadian hair stylist Aliza Esmail called the controversial ‘do “one of the most wearable for almost any hair type,” due to the shift to more “lived in” looks, telling Yahoo News she encourages clients to “work with their natural textures.”

“The bob, it comes and goes — and it comes more often than any other style that we’ve seen out there,” she said.