No matter your face shape, no matter your body type, no matter your hair type, the most universally flattering hair length on anyone tends to be shoulder-length.
A shoulder-length cut works on all face shapes: it's not too long which can make a thin, angular face appear even longer and it's not too short, which can make a round face appear even rounder. This length also works well for all hair types: curly hair cut too short can appear pouf-fy and thin hair can fall flat if grown too long. As for ages, it works beautifully on women of all ages.
Photo: Julianne Hough by Valerie Macon, Getty Images