Philtrum length
Philtrum length : chin height
The length of the philtrum, the groove between the base of the nose and the top of the upper lip, as a fraction of chin height measured from the fold under the lower lip to the bottom of the chin.
Also searched as long philtrum, short philtrum and philtrum to chin ratio.
How to read it
the philtrum is short relative to the chin. That configuration is associated with a youthful lower face, since the philtrum lengthens with age.
philtrum length relative to chin height sits close to the reference mean.
the philtrum is long relative to the chin. Philtrum length increases through adult life; this ratio is one of the more age-sensitive proportions in the lower face.
Both endpoints are soft-tissue landmarks and the chin height is pitch-sensitive (a chin-down photo shortens it). Read with the pitch value in the capture-quality panel.
Reference values by population
| Reference population | Female (mean ± SD) | Male (mean ± SD) | n | Source |
|---|---|---|---|---|
| North American White | 0.381 ± 0.063 | 0.388 ± 0.06 | 2326 | Farkas 1994/2005 (NA White young adults) prov. |
| East Asian | 0.382 ± 0.066 | 0.382 ± 0.063 | 618 | Farkas 2005 (Chinese/Japanese/Vietnamese/Thai pooled); Jayaratne 2012 (Southern Chinese, n=103) prov. |
| South Asian | 0.371 ± 0.064 | 0.382 ± 0.063 | 210 | Farkas 2005 (Indian); Metgudmath 2022 prov. |
| African / African diaspora | 0.386 ± 0.068 | 0.372 ± 0.063 | 300 | Farkas 2005 (African-American, Zulu, Angolan) prov. |
| Middle Eastern | 0.389 ± 0.063 | 0.388 ± 0.06 | 348 | Farkas 2005 (Turkish, Iranian, Egyptian); Al-Sebaei 2015 (Saudi, n=168) prov. |
| Hispanic / Latino | 0.377 ± 0.064 | 0.377 ± 0.062 | 120 | Farkas 2005 (Mexican-American) prov. |
| Not specified — show pooled | 0.381 ± 0.066 | 0.381 ± 0.064 | 3922 | Unweighted pool of the six groups above prov. |
Where these numbers come from
Transcribed from the cited anthropometric literature; SDs of ratios are propagated conservatively (independence assumed). Entries marked prov. await line-by-line audit against the primary tables. See the norm provenance note.
Why every value has an error bar
Every value Canthion reports carries a 1σ uncertainty propagated from MediaPipe Face Mesh's published accuracy (3.96% of inter-ocular distance mean absolute error per landmark, Kartynnik 2019). On a typical photo with 300 px between the pupils, that is about 12 px of wander on every point. Small ratios and angles inherit it, so their intervals are wide. A number without an interval is a number pretending to be more precise than it is.
References
- Farkas, Katic & Forrest (2005). International Anthropometric Study of Facial Morphology in Various Ethnic Groups/Races. J Craniofac Surg 16(4):615–646. doi.org/10.1097/01.SCS.0000171847.58031.9E
Common questions
What is philtrum length?
The length of the philtrum, the groove between the base of the nose and the top of the upper lip, as a fraction of chin height measured from the fold under the lower lip to the bottom of the chin.
How is philtrum length measured from a photo?
It is computed from the face-mesh landmarks (sn, ls, sl, me): dist(sn, ls) / dist(sl, me). Every value carries a 1σ error bar propagated from the landmark detector's published accuracy, with a floor of ± 0.04, so a small difference inside the interval is not a difference.
What is a normal philtrum length?
Reference means and standard deviations from the anthropometric literature, by population. North American White: 0.381 ± 0.063 for women, 0.388 ± 0.06 for men; East Asian: 0.382 ± 0.066 for women, 0.382 ± 0.063 for men; South Asian: 0.371 ± 0.064 for women, 0.382 ± 0.063 for men; African / African diaspora: 0.386 ± 0.068 for women, 0.372 ± 0.063 for men. This value is provisional and awaits line-by-line audit against the primary tables. Your own value is placed on the distribution you choose, as a percentile with its error bar.
What does a low or high philtrum length mean?
Below the mean: the philtrum is short relative to the chin. That configuration is associated with a youthful lower face, since the philtrum lengthens with age. Above the mean: the philtrum is long relative to the chin. Philtrum length increases through adult life; this ratio is one of the more age-sensitive proportions in the lower face.
How reliable is philtrum length from a photograph?
Both endpoints are soft-tissue landmarks and the chin height is pitch-sensitive (a chin-down photo shortens it). Read with the pitch value in the capture-quality panel.
Philtrum against chin is one of the medium-effect traits on the masculinity and femininity scale.
Related measurements
The rest of the lower face set, then the nearest measurements elsewhere on the face. Every one is computed on the same photograph, in the same run, with its own error bar.
Also: how bone-level measurements are taken from a photo · methodology · glossary · all 35 insight pages