Facial Shapes and Hairstyles: Round

A round facial shape is a full-looking face with a round chin and hairline. The widest point is at the cheeks and ears.
Christina Ricci looks amazing even though she is breaking some rules. What works well about this cut is that it acts like a frame that is closing in the sides, which makes her face narrower. Also, the pointed lengths well above her chin have a positive effect of lengthening her chin.
Christina Ricci 2

Christina Ricci 3
Christina Ricci following all the rules.
Christina Ricci with long hair. In my opinion, she looks better with shorter hair.

Drew Barrymore
Ingrid Bergman
Ingrid Bergman 2

Ingrid Bergman 3
Kate Winslett. Good use of color, and I think the center part, breaking the rule, works well to lengthen her face.

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Round

Consider layering the top to achieve fullness while keeping the rest of the cut closer to the head. Short swept-back styles or styles shorter or longer than chin length work well. Place color accents so they appear at the top and below the chin if hair is longer than chin length.

Because the widest part of your face is at the cheeks and ears, you need to avoid having the fullness of the cut here as it will make your face appear wider. Avoid short-short crops and a horizontal or round fringe, chin length hair, and fullness or color accents on the sides.