How It's Measured

How is the philtrum length measured?

The philtrum length is read on a front-facing photograph as the vertical distance between two soft-tissue landmarks on the central upper lip (Naini, 2022). The two landmarks anchor the measurement to the cutaneous philtrum, the dimpled region directly below the nose.

• Sn (subnasale): the point where the columella of the nose meets the upper lip skin, at the centre of the nasal base.

• Ls (labrale superius): the midpoint of the upper lip vermilion border, sitting in the central dip of the Cupid's bow.

The distance from Sn straight down to Ls, measured along the true vertical with the head in natural head position, is the philtrum length. Because Ls is the vermilion border and not the lowest dip of the Cupid's bow, clinical sources sometimes report the closely related mid-philtral height (Sn-Sts) instead. Both anchor the upper lip's vertical position and predict whether the mouth reads youthful or aged.

Why It Matters

Why does the philtrum length matter?

Philtrum length controls how much of the upper teeth shows at rest, how the upper lip drapes, and how youthful the lower face reads. In adult women the mid-philtral height averages 20 ± 2 mm, and in adult men 22 ± 2 mm (Naini, 2022). Shorter values keep the upper incisors slightly visible and let the lip sit fuller and more lifted. Longer values hide the teeth, flatten the upper lip, and pull the lower face toward an older silhouette.

The philtrum elongates with age. Penna and colleagues used a graded classification of perioral ageing to show that progressive lengthening of the cutaneous upper lip is one of the earliest visible signs of midface ageing, together with vermilion thinning and loss of Cupid's bow definition (Penna et al., 2014). Short philtrum length is one of the few facial features whose youthful version actually reads more youthful and not just more average. The subnasal lip-lift was designed around this finding. It works by surgically reducing the Sn-Ls distance by a few millimetres.

Sex and ethnicity both move the band. The classical anthropometric norms were drawn almost entirely from North American Caucasian subjects (Naini, 2022), and revisions in Afro-American and Arabian populations show different baseline lip proportions (Farkas et al., 2000); (Al-Khatib et al., 2015). A single global ideal misreads non-Caucasian faces. The demographic table below shows where each population actually sits.

Demographic Variants

Ideal Philtrum Length by Demographic

Ideal philtrum length varies by population and life stage. The table below shows lit-supported mid-philtral height ranges, with the canonical paper that established each value.