Eye–mouth distance : face length (Pallett)
The only empirically derived "midface ratio": Pallett, Link & Lee (2010) found raters preferred an eye-to-mouth distance of ≈0.36 of face length (hairline to chin).
Depends on the user-placed hairline (trichion) — no detector locates it and it moves with hairstyle.
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the eye-to-mouth distance is short relative to face length (a compact midface).
this proportion sits near the value Pallett et al. identified as the preferred/average configuration.
the eye-to-mouth distance is long relative to face length (a long midface). Note the value depends on the user-placed hairline.
Every consumer app computes a different thing and calls it "midface ratio". This is the one definition with a citation, and it was derived on one population and one sex.
Reference values by population
| Reference population | Female (mean ± SD) | Male (mean ± SD) | n | Source |
|---|---|---|---|---|
| North American White | 0.36 ± 0.03 | 0.36 ± 0.03 | — | Pallett et al. 2010 — preferred value on Caucasian female faces (n=4 experiments); treated as the population-average configuration. Provisional for other groups. prov. |
| East Asian | 0.36 ± 0.03 | 0.36 ± 0.03 | — | Pallett et al. 2010 — preferred value on Caucasian female faces (n=4 experiments); treated as the population-average configuration. Provisional for other groups. prov. |
| South Asian | 0.36 ± 0.03 | 0.36 ± 0.03 | — | Pallett et al. 2010 — preferred value on Caucasian female faces (n=4 experiments); treated as the population-average configuration. Provisional for other groups. prov. |
| African / African diaspora | 0.36 ± 0.03 | 0.36 ± 0.03 | — | Pallett et al. 2010 — preferred value on Caucasian female faces (n=4 experiments); treated as the population-average configuration. Provisional for other groups. prov. |
| Middle Eastern | 0.36 ± 0.03 | 0.36 ± 0.03 | — | Pallett et al. 2010 — preferred value on Caucasian female faces (n=4 experiments); treated as the population-average configuration. Provisional for other groups. prov. |
| Hispanic / Latino | 0.36 ± 0.03 | 0.36 ± 0.03 | — | Pallett et al. 2010 — preferred value on Caucasian female faces (n=4 experiments); treated as the population-average configuration. Provisional for other groups. prov. |
| Not specified — show pooled | 0.36 ± 0.03 | 0.36 ± 0.03 | — | Pallett et al. 2010 — preferred value on Caucasian female faces (n=4 experiments); treated as the population-average configuration. Provisional for other groups. 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). For a typical 300 px inter-pupil photo that is ≈12 px per landmark, which is why small ratios and angles get wide intervals. A number without an interval is a number pretending to be more precise than it is.
References
- Pallett, Link & Lee (2010). New "golden" ratios for facial beauty. Vision Res 50(2):149–154. doi.org/10.1016/j.visres.2009.11.003
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