Straight and rounded hairlines
A straight hairline runs across the forehead in a fairly level line, with little dip at the temples. A rounded hairline, sometimes called bell-shaped, curves down at the sides like an arch, so the forehead looks framed by hair. In a study of 456 Japanese adults, a straight front was the most common shape in men (about 46 percent) and the second most common in women (about 36 percent), while a rounded front was the most common in women (about 39 percent) and much rarer in men (about 11 percent). Both are typical of hairlines that have not receded.
Based on: Kashiyama et al. 2021
Widow's peak
A widow's peak is a V-shaped point of hair at the centre of the forehead. Dermatologists regard it as a normal variation in how the hairline forms, and how common it seems depends on how strictly a point is defined: the same Japanese study found a peak in about three in ten adults, while studies of women in other countries have reported far higher figures. A peak can sit on a straight, rounded or M-shaped hairline. The hairline check names one shape and measures the temple corners separately; when both corners sit clearly behind the centre, it calls the outline M-shaped, point or no point, because the corners are what matter for hair loss.
Based on: Kyriakou et al. 2021; Kashiyama et al. 2021
M-shaped hairlines
In an M-shaped hairline the corners at the temples sit further back than the centre, so the front edge traces a broad letter M. It is very common in men: in the Japanese study about 43 percent of men had an M-shaped front, and about 83 percent had some hairless notch at the temples, compared with about 18 and 48 percent of women. An M can be the adult shape a hairline settles into, or the early stage of male-pattern hair loss, where it matches Norwood II and III. The shape alone cannot tell you which. Depth and, above all, change over time can.
Based on: Kashiyama et al. 2021; Norwood 1975
Uneven hairlines
Few hairlines are perfectly symmetrical. Studies that measured hairlines precisely found small differences between the left and right sides in ordinary volunteers, and a cowlick or a habitual parting can make one side look higher than the other. Unevenness that has always been there is shape. Unevenness that appears or grows is worth a closer look: tight ponytails, braids, extensions or headwear that pull on the same spot can cause traction alopecia, which thins the edge of the hairline and can become permanent if the pulling continues.
Based on: Nusbaum & Fuentefria 2009; American Academy of Dermatology
What shape tells you about hair loss
On its own, very little. Pattern hair loss in men usually announces itself by change: temple corners that deepen over months, hairs at the edge that become finer, a crown that shows more scalp. In women, female-pattern thinning usually leaves the front hairline in place and thins the top instead, which the Ludwig scale describes. A few changes are worth a dermatologist's opinion soon, whatever your shape: a hairline that recedes quickly as a band along the front and sides, especially with eyebrow loss, sudden shedding and patchy bald spots.
Based on: American Academy of Dermatology
How the hairline check names your shape
The free GlowUp Face check finds the edge of your hair in a front photo and labels it with one of five shapes: straight, rounded, widow's peak, M-shaped or uneven. The label describes the outline and does not set the range. The Norwood range comes from the measurements, chiefly how far each temple corner sits behind the centre and how high the hairline sits against your own facial proportions, so deep corners raise the range whatever the label says, and a widow's peak on its own does not. A fringe, a hat line or hair falling over the forehead can hide the edge; the check says so when it cannot see enough.