Jill Turnbull, a session hairstylist and founder of a botanical hair care line, said: “This 2-in-1 haircut combines a shorter interior layer, often a bob, undercut or soft shag, with longer top layers that blend over it.” When the hair is worn down, the shorter interior is concealed by the longer exterior layers. When worn in a half up, half down style, the bob shape is exposed.

“Styled differently [tucked around the ears or blown in a different way], it can transform from a sleek, elegant look to something punk or shaggy. It is like two haircuts combined, hence the name,” Zoey Taylor, a hair specialist at Curls Queen, added.

On TikTok, a simple search for the style will generate videos featuring women at varying salons getting the unique cut in recent months. However, while the current online proliferation makes it seem like the technique was just recently established, the Korean 2-in-1 has been in existence for years. Turnbull said the editorial styling of K-pop stars in the early 2020s first popularized the cut as many artists were pictured with it. This subsequently led to its favor among teenagers and young adults in “trendy” Seoul-based salons.

“Although not a new concept, the Korean version refined the silhouette, and that interpretation is what gained global popularity,” Turnbull added. That said, not everyone should be asking for the Korean 2-in-1; only specific hair types are compatible. “This haircut is best suited for medium to thick textures with a straight to softly wavy pattern. These textures hold their shape clearly and provide definition to the contrast. It can also work on finer or highly textured hair, which requires more technical cutting and careful weight distribution to maintain balance,” Turnbull said.

Curly or coily hair won’t result in the same dimension and movement. “It can be customized for curlier textures with the right layering and styling techniques — but make sure your stylist knows their way around a razor or texturizing shears,” celebrity hairstylist Jessica Ruby told WWD.