Facial thirds: middle versus lower face

What facial thirds is

The classic way to judge facial balance is to divide the face into three equal bands: hairline to brows, brows to the base of the nose, and the base of the nose to the chin. LookFlex measures the second and third bands and compares them as a ratio. A value of 1.0 means the middle and lower thirds are exactly equal.

Real faces rarely have equal thirds, and in LookFlex's reference set the lower third ran a little longer for men. The range LookFlex uses reflects that, and the reading is best understood as a description of where your face carries its length.

How LookFlex measures it

LookFlex measures the vertical distance from the point between the brows to the base of the nose, then from the base of the nose to the tip of the chin, and divides the first by the second. The head is levelled and corrected for nod first because vertical distances are sensitive to chin-up and chin-down angles.

The upper third is not measured. The top of the face mesh sits below the real hairline, so there is no reliable landmark for it, and hair, hats and receding hairlines would make any estimate unfair. This is a deliberate limit rather than an oversight.

The calculation: thirds = (brow-point to nose-base height) ÷ (nose-base to chin height).

Landmarks used

LookFlex reads these points from the 478-landmark face mesh. The numbers are each point's index in that mesh.

• Point between the brows: 9
• Base of the nose: 2
• Tip of the chin: 152

The full pipeline, including how pose and mirror-averaging reduce noise, is on how LookFlex measures your face.

Typical and scoring ranges

LookFlex shows two ranges. The typical range is the middle half of its reference set, from the 25th to the 75th percentile: half of the faces fell inside it. The scoring range is where a reading earns a closeness score of 100; outside it the score falls smoothly, with no cliff at the edge. Both differ for men and women, and LookFlex blends the two if you choose Other or prefer not to say. Unit: unitless ratio.

How to read your result

"The range" here means the scoring range. The impressions below are common styling descriptions, not research findings. What research does show is in the next section.

• Below the range: The lower third is longer than the middle: a strong chin and jaw presence.
• Inside the range: The ratio of the middle to the lower third sits inside the scoring range for your sex.
• Above the range: The middle third is the longer one: a refined lower face.

What the research says

Limited evidence Measurements of real faces show equal thirds are not a norm, but no study sets an ideal balance.

• Real faces varied widely, and classical rules such as perfectly equal facial thirds fitted only a few people (Farkas et al., 1985).
• The popular golden-ratio face mask fits many faces poorly, especially non-European ones (Holland, 2008).
• Faces were rated best close to an average face rather than at a classical ideal (Pallett et al., 2010).

No study we cite tests LookFlex's own ranges. They come from the calibration described on the methodology page, and every source is listed under References below.

What influences it

Mostly fixed

• The vertical length of the nose and the height of the chin, both skeletal.
• Age, which can change the soft tissue of the lower face.

Things that move the reading

• Mouth position. An open mouth drops the jaw and lengthens the lower third.
• Facial hair. A fuller beard extends the visual chin, a trimmed one shortens it.
• Head pitch. Chin up shortens the lower third, chin down lengthens it.

How to improve how it reads

These suggestions change how the measurement reads or how well the photo captures it. Styling tips are common practice rather than tested in research, and none of them promises a change in bone structure.

• Keep your lips gently closed and your teeth just apart when you scan.
• A neater, shorter beard or stubble cut can balance a long lower third, and a defined line under the jaw keeps it clean.
• Hairstyles with a fringe or height change the upper third you cannot measure, and shift the overall impression of balance.
• When you scan, keep your head over your shoulders so the chin neither juts nor tucks.

Common myths

Myth: The thirds must be exactly equal.

That is a Renaissance drawing canon, not a measured norm: in measurements of real faces, classical rules such as equal facial thirds fitted only a few people (Farkas et al., 1985). LookFlex's ranges are 0.85–0.98 for men and 0.92–1.04 for women because real lower thirds run longer on average.

Myth: LookFlex measures all three thirds.

It measures two. The hairline is not a reliable landmark on the face mesh, so the upper third is left out.

How it feeds your score

This measurement is one input to one sub-score, which then combine into your Glow Score:

• Harmony: 15% of the sub-score. Harmony carries 22% of the Glow Score.

Precision. Every reading of this measurement comes with a 95% margin, estimated by measuring your photo three times. Across the reference set the median margin was ±0.017: a retake in similar conditions usually lands within that much of the first reading. A change between two scans counts as real only when it is bigger than both scans' margins combined.

Confidence. LookFlex starts this measurement at a confidence of 80% and lowers it when your head angle, the lighting or image quality weakens the reading. The weight of each input in a sub-score scales with its confidence. Details are on the methodology page.