How to improve face symmetry
Most of what you measured was the photo. Check that first.
Read this first
Structural asymmetry — different bone on the two sides — does not change without surgery, and it is universal: nobody is symmetric and small differences are the norm rather than a fault. But most of what people measure is not structural at all. Head rotation of a few degrees compresses one side of the face in the image, and a symmetry tool measures the image.
Improving facial symmetry starts with finding out how much of yours is real. Turning a few degrees toward the camera compresses one half of the face in the photograph, and every symmetry measurement — including this site's — measures the photograph rather than the skull. Re-shoot square-on to the lens, at eye level, with the same light falling on both sides, and a large share of measured asymmetry disappears. What remains splits in two. Skeletal asymmetry is permanent and normal; every published measurement finds it in everyone, and it is not something to fix. Habitual asymmetry does move over months: chewing predominantly on one side, sleeping on one side, and a persistent head tilt all shape soft tissue and muscle bulk unevenly. Those are worth changing. Nothing else on the usual list does anything.
What actually works
Re-shoot square-on before concluding anything
Camera at eye level, lens centred on your nose, both sides lit the same. Compare the two readings. If they differ by more than a few points, the first one was measuring your pose.
Change the habits that are one-sided
Chewing on one side, sleeping face-down on one side, holding a phone with one shoulder. These shape muscle and soft tissue over months, and they are the only asymmetry with an actual lever attached.
Look at the neck and shoulders, not the face
A persistent head tilt is usually postural rather than facial, and it shows up in every photograph as facial asymmetry. It is also the one on this list most likely to have a physiotherapist's answer.
Accept the rest, and stop measuring weekly
Structural asymmetry is universal and permanent. Measuring it weekly produces noise from your photography and nothing else, and the habit is worse for most people than the asymmetry.
Measure it, so you know whether anything moved
How symmetric is my face?Mean deviation of twelve mirrored landmark pairs, as a percentage.
Questions
Do face exercises improve symmetry?
There is no evidence that they do, and a plausible mechanism only for the muscle-bulk component, which is small. Training one side deliberately is more likely to introduce an asymmetry than to remove one.
Why is my face more asymmetric in photos than in the mirror?
Because a mirror shows you a flipped image you have seen thousands of times and a photo shows you the unflipped one you have not. The asymmetry is identical; only your familiarity with it differs.
How symmetric is a normal face?
Every population study finds meaningful asymmetry in everyone measured. There is no threshold that separates normal from abnormal, and tools that quote a percentage — including this one — are describing a photograph, not a diagnosis.