Facial thirds
Face height split into three bands: hairline to the point between the brows, that point down to the base of the nose, and the base of the nose to the bottom of the chin. Each is given as a percentage of the total.
Also searched as rule of thirds face, equal facial thirds and upper middle lower third of the face.
Depends on the user-placed hairline (trichion): no detector locates it, and it moves with hairstyle.
Measure yours →How to read it
Typical adult faces show a lower third slightly larger than the middle third, and an upper third that varies enormously with hairline. Nothing in the literature supports reading a "short" or "long" third as a flaw. Equal thirds are the exception in every population studied.
0% of a Southern Chinese sample had equal thirds; 91% of Saudi men and 88% of Saudi women had a lower third larger than the middle. In practice the lower third is usually the largest.
Conformity in published samples: east asian 0% · middle east m 5%
The upper third depends entirely on the user-placed hairline; the middle and lower thirds are the meaningful comparison.
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
- Al-Sebaei (2015). The validity of three neo-classical facial canons in young adults originating from the Arabian Peninsula. Head Face Med 11:4. doi.org/10.1186/s13005-015-0064-y
- Khoshab et al. (2022). Historical Tools of Anthropometric Facial Assessment: A Systematic Raw Data Analysis on the Applicability of the Neoclassical Canons and Golden Ratio. Aesthet Surg J 42(1):NP1–NP10. doi.org/10.1093/asj/sjab339
Common questions
What are facial thirds?
Face height split into three bands: hairline to the point between the brows, that point down to the base of the nose, and the base of the nose to the bottom of the chin. Each is given as a percentage of the total. The neoclassical canon claims three equal thirds (33.3% each).
How are facial thirds measured from a photo?
They are computed from the face-mesh landmarks (tr, g, sn, me): [dist(tr,g), dist(g,sn), dist(sn,me)] / dist(tr,me). Every value carries a 1σ error bar propagated from the landmark detector's published accuracy, with a floor of ± 1, so a small difference inside the interval is not a difference.
How should facial thirds be read?
Typical adult faces show a lower third slightly larger than the middle third, and an upper third that varies enormously with hairline. Nothing in the literature supports reading a "short" or "long" third as a flaw. Equal thirds are the exception in every population studied.
How reliable are facial thirds from a photograph?
The upper third depends entirely on the user-placed hairline; the middle and lower thirds are the meaningful comparison.
Equal thirds is one of the neoclassical canons, and the conformity figures for it across four measured populations are on that page.
Related measurements
The rest of the whole 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