Eye aspect ratio: how open your eyes are

What eye aspect ratio is

Eye aspect ratio describes how open your eyes are compared with how wide they are. A low value means a narrow opening, as with hooded or deep-set eyes. A high value means a taller, rounder opening. In the app this measure is labelled Eye shape.

Almond shapes sit in the middle of the scale, and rounder shapes are often described as softer and more youthful. Because eyes are never perfectly still, the reading moves with alertness, light and expression, which is why it is one of the more changeable numbers on your scan.

In the LookFlex app this measurement appears as Eye shape.

How LookFlex measures it

LookFlex measures the vertical opening at six pairs of points along the upper and lower lid of each eye, averages them into one lid height, and divides that by the average eye width from inner to outer corner. Averaging several points keeps one slightly off landmark from skewing the result.

The ratio is unitless, so it does not depend on image size. It does depend on how open your eyes were at the moment of capture, which is why scanning with relaxed, natural eyes matters.

The calculation: aspect = average lid opening height ÷ average eye width.

Landmarks used

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

• Upper and lower lid points: 159, 145, 158, 153, 160, 144, 386, 374, 385, 380, 387, 373
• Inner eye corners: 133, 362
• Outer eye corners: 33, 263

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: A narrow, hooded opening. Good front lighting stops shadow from narrowing it further in photos.
• Inside the range: A classic almond opening: balanced between narrow and round.
• Above the range: A round, open eye: expressive and youthful. Heavy brows or low lighting can make it look more tired than it is.

What the research says

Limited evidence No study sets an ideal eye opening; the best evidence is that tiredness changes how open the eyes look.

• After a night of sleep loss, faces were seen as having droopier eyelids, redder and more swollen eyes and darker under-eye circles (Sundelin et al., 2013).
• We found no study that identifies an attractive or healthy eye-opening ratio, so LookFlex's range is a convention.

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

• Lid structure, the depth of the eye socket and the fold of the upper lid, all largely inherited.
• Age, which can change the upper lid and the visible opening.

Things that move the reading

• Tiredness. After sleep loss, faces looked as though they had droopier eyelids and more swollen eyes (Sundelin et al., 2013).
• Light. Bright light makes people squint and lowers the ratio, flat soft light lets the eyes open.
• Expression. A broad smile pushes the lower lid up, surprise lifts the upper lid.
• Lash and lid makeup, which changes how open the eye looks without moving the landmarks.

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.

• Sleep is the evidence-backed lever: sleep loss made lids look droopier and eyes more swollen (Sundelin et al., 2013).
• Scan facing a window or soft light source so you are not squinting, with a relaxed neutral face.
• Curling lashes and keeping the brow clear of the lid give a more open look in photos.
• If one lid droops noticeably or the change is recent, mention it to a doctor. That is a medical question, not a styling one.

Common myths

Myth: Bigger, rounder eyes are always better.

Round eyes are often described as softer and almond eyes as sharper. LookFlex's ranges (0.22–0.30 for men, 0.24–0.32 for women) are a lean toward the middle, and a reading outside them is a description, not a defect.

Myth: Eye shape tells you someone's ancestry or health.

It does not. LookFlex never infers ancestry from a face, and it never treats eyelid shape as a flaw.

How it feeds your score

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

• Eyes: 15% of the sub-score. Eyes carries 17% 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 ±0.0097: 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.