Mouth width
Mouth width : alar base width
How wide the mouth is from corner to corner, as a multiple of the width of the nose.
Also searched as mouth width to nose width, wide mouth and narrow mouth.
How to read it
the mouth is narrow relative to the nose for the reference group, or the nose is comparatively wide; the ratio does not distinguish which.
mouth width relative to nose width sits close to the reference mean.
the mouth is wide relative to the nose for the reference group.
Only 8.7% of a Southern Chinese sample conformed. Population means range from ~1.3 (African reference) to ~1.6 (NA White reference).
Conformity in published samples: east asian 9%
Reference values by population
| Reference population | Female (mean ± SD) | Male (mean ± SD) | n | Source |
|---|---|---|---|---|
| North American White | 1.599 ± 0.151 | 1.562 ± 0.15 | 2326 | Farkas 1994/2005 (NA White young adults) prov. |
| East Asian | 1.296 ± 0.124 | 1.273 ± 0.114 | 618 | Farkas 2005 (Chinese/Japanese/Vietnamese/Thai pooled); Jayaratne 2012 (Southern Chinese, n=103) prov. |
| South Asian | 1.418 ± 0.138 | 1.397 ± 0.136 | 210 | Farkas 2005 (Indian); Metgudmath 2022 prov. |
| African / African diaspora | 1.325 ± 0.126 | 1.299 ± 0.12 | 300 | Farkas 2005 (African-American, Zulu, Angolan) prov. |
| Middle Eastern | 1.508 ± 0.144 | 1.479 ± 0.141 | 348 | Farkas 2005 (Turkish, Iranian, Egyptian); Al-Sebaei 2015 (Saudi, n=168) prov. |
| Hispanic / Latino | 1.412 ± 0.139 | 1.392 ± 0.137 | 120 | Farkas 2005 (Mexican-American) prov. |
| Not specified — show pooled | 1.42 ± 0.189 | 1.394 ± 0.182 | 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, Hreczko, Kolar & Munro (1985). Vertical and horizontal proportions of the face in young adult North American Caucasians: revision of neoclassical canons. Plast Reconstr Surg 75(3):328–338. pubmed.ncbi.nlm.nih.gov/3883374/
- Jayaratne, Deutsch, McGrath & Zwahlen (2012). Are Neoclassical Canons Valid for Southern Chinese Faces? PLoS ONE 7(12):e52593. doi.org/10.1371/journal.pone.0052593
- 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 mouth width?
How wide the mouth is from corner to corner, as a multiple of the width of the nose. The neoclassical "naso-oral canon" claims 1.5.
How is mouth width measured from a photo?
It is computed from the face-mesh landmarks (ch_R, ch_L, al_R, al_L): dist(ch_R, ch_L) / alarWidth. 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 mouth width?
Reference means and standard deviations from the anthropometric literature, by population. North American White: 1.599 ± 0.151 for women, 1.562 ± 0.15 for men; East Asian: 1.296 ± 0.124 for women, 1.273 ± 0.114 for men; South Asian: 1.418 ± 0.138 for women, 1.397 ± 0.136 for men; African / African diaspora: 1.325 ± 0.126 for women, 1.299 ± 0.12 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 mouth width mean?
Below the mean: the mouth is narrow relative to the nose for the reference group, or the nose is comparatively wide; the ratio does not distinguish which. Above the mean: the mouth is wide relative to the nose for the reference group.
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