Lip ratio
Upper : lower vermilion height
The height of the red part of the upper lip at its midline, divided by the same measure on the lower lip.
Also searched as upper to lower lip ratio, ideal lip ratio and lip proportions.
How to read it
the upper vermilion is thin relative to the lower. This is the commonest configuration in every reference group. The widely quoted 1:1.6 "ideal" puts most humans below it by construction.
upper and lower vermilion heights are in the typical proportion for the reference group.
the upper vermilion is comparatively full relative to the lower.
Lip fillers, lip-liner overdrawing and pursing all change this value; it is a poor biological signal in the selfie population.
Reference values by population
| Reference population | Female (mean ± SD) | Male (mean ± SD) | n | Source |
|---|---|---|---|---|
| North American White | 0.842 ± 0.206 | 0.848 ± 0.207 | 2326 | Farkas 1994/2005 (NA White young adults) prov. |
| East Asian | 0.85 ± 0.197 | 0.857 ± 0.188 | 618 | Farkas 2005 (Chinese/Japanese/Vietnamese/Thai pooled); Jayaratne 2012 (Southern Chinese, n=103) prov. |
| South Asian | 0.9 ± 0.202 | 0.905 ± 0.205 | 210 | Farkas 2005 (Indian); Metgudmath 2022 prov. |
| African / African diaspora | 0.88 ± 0.181 | 0.885 ± 0.185 | 300 | Farkas 2005 (African-American, Zulu, Angolan) prov. |
| Middle Eastern | 0.842 ± 0.206 | 0.85 ± 0.205 | 348 | Farkas 2005 (Turkish, Iranian, Egyptian); Al-Sebaei 2015 (Saudi, n=168) prov. |
| Hispanic / Latino | 0.857 ± 0.188 | 0.864 ± 0.192 | 120 | Farkas 2005 (Mexican-American) prov. |
| Not specified — show pooled | 0.864 ± 0.236 | 0.869 ± 0.234 | 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
- Kar, Muluk, Bafaqeeh & Cingi (2018). Is it possible to define the ideal lips? Acta Otorhinolaryngol Ital 38(1):67–72. doi.org/10.14639/0392-100X-1511
- 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 lip ratio?
The height of the red part of the upper lip at its midline, divided by the same measure on the lower lip. Frequently claimed "ideal" of 1:1.6 (0.62) is asserted from the golden ratio, not derived empirically; measured population means sit nearer 0.85.
How is lip ratio measured from a photo?
It is computed from the face-mesh landmarks (ls, sto_upper, sto_lower, li): dist(ls, sto_upper) / dist(sto_lower, li). Every value carries a 1σ error bar propagated from the landmark detector's published accuracy, with a floor of ± 0.06, so a small difference inside the interval is not a difference.
What is a normal lip ratio?
Reference means and standard deviations from the anthropometric literature, by population. North American White: 0.842 ± 0.206 for women, 0.848 ± 0.207 for men; East Asian: 0.85 ± 0.197 for women, 0.857 ± 0.188 for men; South Asian: 0.9 ± 0.202 for women, 0.905 ± 0.205 for men; African / African diaspora: 0.88 ± 0.181 for women, 0.885 ± 0.185 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 lip ratio mean?
Below the mean: the upper vermilion is thin relative to the lower. This is the commonest configuration in every reference group. The widely quoted 1:1.6 "ideal" puts most humans below it by construction. Above the mean: the upper vermilion is comparatively full relative to the lower.
How reliable is lip ratio from a photograph?
Lip fillers, lip-liner overdrawing and pursing all change this value; it is a poor biological signal in the selfie population.
Lip proportions sit on the dimorphism scale; that page gives the direction and the size of the difference.
Related measurements
The rest of the lips 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