What the term actually describes
Forehead-height ratio divides total face height — trichion (the hairline's midpoint) down to menton (the chin's lowest point) — by forehead height alone, trichion down to glabella (the point between the brows).
Studies analyzing faces rated attractive report this figure at roughly 3.1 to 3.4, and cite it differently by sex: one figure puts it at 3.38 in men and 3.13 in women, a companion figure at 3.45 and 3.17.
A higher number means a relatively shorter forehead against total face height; a lower number means a relatively taller one.
Why the anchor point is the real problem
Every landmark in this ratio except one is a fixed point on the skull or soft tissue: glabella sits on bone, menton on bone. Trichion is different — it's defined by where hair grows, not by anatomy underneath it:
- Hairline recession — a natural, common change with age that pushes trichion upward with no change to the forehead bone itself.
- Styling — bangs, a hairline trim, or product that reshapes the visible hairline edge shifts the measured point session to session.
- Photo lighting and hair color — low contrast between skin and hair at the hairline makes the exact boundary harder to place consistently even on a single photo.
A ratio can only be as stable as its least stable landmark, and trichion is the one landmark here with no bony reference at all.
A second sign the number itself is unsettled
Beyond the landmark problem, sources reporting what reads as the same measurement don't agree on the figure. One cited male ratio is 3.38, a separate citation for a similarly described male sample gives 3.45 — a gap too large to be rounding.
That gap more likely reflects differing sample composition or measurement protocol between studies than a single settled constant. Treating either number as a precise target overstates how settled the underlying research actually is.
Not the same claim as "equal facial thirds"
This ratio gets confused with the classical facial-thirds rule because both involve the forehead region, but they're different claims. Facial thirds argues the upper, middle, and lower face bands should be close to equal height — a claim Farkas's anthropometric research found describes only a minority of real faces even within one population.
Forehead-height ratio is narrower: a single face-height-over-forehead-height number cited from attractiveness-rated samples, not a population-norm proportion canon. They share a landmark (glabella) but answer different questions.
Where this fits next to what Mogalytics actually reads
Mogalytics does not compute or display a forehead-height ratio or a facial-thirds number. Its six-measurement composite reads live from a front-facing camera feed and doesn't include a trichion-anchored measurement at all — the hairline-instability problem above is one reason a self-measurement tool built for repeatable, camera-visible readings would avoid anchoring to it.
Mogalytics makes no claim of parity with any other site's forehead-ratio or facial-thirds assessment.
Related reads
Forehead height sits next to a few ideas Mogalytics does track. If you're auditing the rest:
- Facial thirds — the related but distinct "equal thirds" canon, and why Farkas's own research found it doesn't hold across populations.
- Golden ratio face — another whole-face proportion claim with its own peer-reviewed critique literature.
- Midface ratio — the measurement Mogalytics does read live, anchored to the eye line and upper lip rather than the hairline.
- Brow ridge — shares the glabella-adjacent brow region, but reads bone projection on a side profile, not vertical height on a frontal shot.
- Why face-rating scores swing between scans — the camera and pose sensitivities behind every one of these self-measurements.