Facial symmetry explained: how it’s measured and what it does to your score

Facial symmetry is how closely the left half of a face mirrors the right. Every face is a little asymmetric: one brow sits higher, the nose leans a degree, one mouth corner lifts more. The attractiveness test measures symmetry from a camera scan in your browser and uses it as one of six components of its score. This guide explains how it is measured, how much it matters, and what moves it.

How symmetry is measured

The scan uses Google’s MediaPipe Face Landmarker, which places 478 points on the face in every camera frame. Most points have a mirror partner: the outer corner of the left eye pairs with the outer corner of the right, the left mouth corner with the right, and so on down the jaw. The measurement has three steps:

1. Align. The face is rotated so the line between the eyes is level and centred, so a tilted head or an off-centre position does not count as asymmetry.
2. Mirror. Each point on one side is reflected across the facial midline and compared with its partner on the other side.
3. Normalise. The average mismatch is divided by the distance between the outer eye corners, so the result does not depend on how close you were to the camera.

Because the scan captures 8 frames at the front angle and takes the median of each point, one frame with a blink or a twitch does not register as asymmetry. The report shows how much the symmetry value varied across those frames.

How it enters the score

Symmetry carries 20% of the attractiveness score. A typical face, with a left–right mismatch of about 3% of the eye span, scores 50 on the component. A face that mirrors more closely scores higher, up to 74 for a perfect mirror; a visible lean or a markedly higher eye scores lower. Symmetry adds to the score in the same way averageness does: both describe a face that is closer to the population’s centre than most. The methodology gives the formula.

The report also breaks symmetry down by region (eyes, brows, nose, mouth, jaw), so you can see whether a low value comes from one feature or from the whole face.

How much symmetry matters

Symmetry is one of the three geometric features most consistently linked to rated attractiveness, alongside averageness and sexual dimorphism. In studies where symmetry is manipulated while everything else is held constant, raters prefer the more symmetric version. The effect is real but modest, and it shrinks when other cues are present, which is why it is one component among six and not the score.

Faces built by mirroring one half of a photo often look odd, partly because they also mirror lighting and skin detail, and partly because nobody has a face like that. The scan measures your real face, so a high symmetry value means your two sides are closely matched, not that they are copies.

Why your photos look different from your mirror

A mirror shows you a flipped face, the one you see every day. A photo shows the unflipped face other people see. Your own asymmetries are therefore reversed in every photo, which is why a photo of yourself can look slightly wrong to you and normal to everyone else. Neither view is more accurate. The scan measures the unflipped face.

What moves the number

• Head turn. Turning a few degrees makes the nearer half of the face look wider. The front capture only fires when yaw is within ±6°, but smaller turns still shift the result slightly.
• Expression. A lopsided smile, one raised brow or a half squint moves points on one side only. Keep a neutral face.
• Lens distance. A phone held close exaggerates whatever is nearest to it, including any small offset between your face and the lens.
• Light. Strong light from one side puts the other side in shadow, where landmarks are placed less precisely.
• Hair, glasses, beard. When part of the outline is covered, the model estimates where the points are instead of seeing them.

Real asymmetry has causes too: uneven jaw growth, dental work, a past injury, sleeping on one side, and age. Most are small and stable; they show up in every scan.

How to get a fair reading

1. Prop the phone at eye level, centred on your nose, an arm’s length away or further.
2. Face soft, even light from the front, such as a window.
3. Keep a relaxed, neutral expression with your mouth closed.
4. Pull your hair off your face and jaw and take off glasses.
5. Scan twice. If the two symmetry values agree, the asymmetry is in your face, not the setup.

Symmetry is not proportion

Symmetry compares your left side with your right. Proportions compare parts of the face with each other: the vertical thirds from hairline to brow, brow to nose base and nose to chin, the horizontal fifths across the eyes, and eye spacing. A face can be highly symmetric with unusual proportions, or the reverse. The score treats them as separate components, and the canthal tilt guide explains why your two eyes can measure differently.

To see where your own face sits, run the attractiveness test. The free result is the score and its tier; the report shows the symmetry component and its regions.