Face measurement terms, in plain English
This glossary defines the terms face analysis apps and online guides use for facial proportions, eye shape, symmetry and scoring, from canthal tilt and facial thirds to reference ranges and noise floors. Each entry gives a general definition, then says plainly whether MaxxLook measures the term, approximates it with a proxy, or does not measure it at all.
Landmarks and the face mesh
Every measurement in a face analysis starts from points placed on a photo. These two terms describe those points; how face analysis apps work walks through the rest of the pipeline.
Facial landmarks (also called face keypoints)
Points placed on recognizable parts of a face in an image, such as the corners of the eyes, the tip of the nose and the outline of the jaw. Measurements of proportion, spacing and symmetry are distances and angles between these points. In MaxxLook: MaxxLook places landmarks on your front photo and groups them into regions such as the eyes, brows, nose, lips, cheeks, jaw and chin, and it estimates ear and neck points because the detection model has none.
Face mesh (478 points) (also called dense face landmarks)
A dense net of landmarks that covers the whole surface of the face instead of a handful of anatomical points. Google’s MediaPipe Face Landmarker produces 478 of them: 468 across the face and 10 that outline the irises. In MaxxLook: MaxxLook runs this mesh on the front photo for all of its geometry and measures each region’s bounding box, center, extreme points or left and right halves rather than single anatomical points.
Proportions
Proportion terms compare the size of one part of the face with another. The facial thirds guide shows how to measure the vertical split yourself, and the free face shape tool gives a quick in-browser reading.
Facial thirds (also called vertical thirds)
A convention that divides face height into an upper band (hairline to brows), a middle band (brows to the base of the nose) and a lower band (nose base to chin) and compares them. Equal bands are a guideline from portrait drawing, not a standard faces are expected to meet. In MaxxLook: MaxxLook approximates the thirds by cutting the front-photo mesh at its top, the brow center, the nose center and the chin-region center and scoring how balanced the three parts are, and because the mesh top sits below the hairline its numbers will not match a hairline-based check.
Facial fifths (also called rule of fifths)
A convention that divides face width into five vertical strips of about one eye-width each: the outer face to each outer eye corner, each eye, and the gap between the eyes. It is used mostly in drawing and portraiture to describe horizontal proportion. In MaxxLook: MaxxLook does not measure facial fifths.
Face length-to-width ratio
Face height divided by face width, describing whether a face reads longer or wider overall. Where the top, bottom and sides are taken from changes the result, so figures from different sources are rarely comparable. In MaxxLook: MaxxLook measures it, with one caveat: it uses the height and width of a box drawn around all front-photo points, which includes the estimated ear and neck points.
Facial width-to-height ratio (FWHR)
Cheekbone-to-cheekbone width divided by the height of the upper face, usually from the brow line or upper eyelids to the upper lip. It leaves out the forehead and the lower face, which makes it a different number from face length-to-width. In MaxxLook: MaxxLook does not measure FWHR.
Bizygomatic width (also called cheekbone width)
The distance between the most outward points of the two cheekbones (the zygomatic arches), which is usually the widest part of the face. Anthropometry uses it as a standard width and as the denominator in several ratios. In MaxxLook: MaxxLook approximates it as cheek-region width divided by face width, taken from the front-photo mesh rather than from the cheekbones themselves.
Bigonial width and jaw-to-cheek ratio (also called jaw width)
The distance between the two back corners of the lower jaw (the gonia). Divided by cheekbone width it gives a jaw-to-cheek ratio, which describes how the width of the lower face compares with the width at the cheeks. In MaxxLook: MaxxLook does not locate the gonial points or compute a bigonial-to-bizygomatic ratio.
Eyes and brows
Eye and brow measurements involve small distances, so a slight head roll or a change in expression moves them more than most. The canthal tilt guide covers the most searched of them in detail.
Canthal tilt (also called eye tilt)
The slope of the line between the inner and outer corner of an eye, given in degrees from horizontal. It is called positive when the outer corner is higher, negative when it is lower and neutral when the two are level. In MaxxLook: MaxxLook measures a proxy, eye-region tilt, which is the angle between the outermost points of each eye region with the iris included, reported as a size without a positive or negative sign and not as the inner-to-outer corner angle.
Eye spacing and interpupillary distance (also called IPD)
How far apart the eyes sit, usually compared with the width of the face. Interpupillary distance is the specific gap between the centers of the two pupils, the figure opticians use to fit glasses. In MaxxLook: MaxxLook approximates eye spacing as the distance between the centers of the two eye regions divided by face width, which is a ratio rather than a pupil-to-pupil distance in millimeters.
Intercanthal distance (also called inner eye-corner distance)
The gap between the inner corners of the two eyes (the medial canthi), across the bridge of the nose. Compared with eye width or face width, it describes how close-set or wide-set the eyes appear. In MaxxLook: MaxxLook does not measure intercanthal distance; its eye-spacing reading uses eye-region centers instead.
Brow tilt and brow height (also called eyebrow angle)
Brow tilt is the slope of an eyebrow from its inner end to its outer end, and brow height is how far it sits above the eye. Both shift with expression and grooming more than most facial measurements. In MaxxLook: MaxxLook measures both as region proxies: the tilt of each brow region as a magnitude, and brow height divided by face height.
Nose, lips and jaw
Several of these terms come from side-view analysis. MaxxLook takes its geometry from the front photo only, so most of them are listed here for reference and are not part of a MaxxLook scan.
Nasal index
Nose width divided by nose height, multiplied by 100. In anthropometry the width is taken across the nostrils at their widest and the height from the root of the nose to its base. In MaxxLook: MaxxLook uses a loose proxy, the width divided by the height of the nose-region box on the front photo, which follows the same idea but not the same anatomical points.
Nasolabial angle
The angle where the underside of the nose meets the upper lip, seen from the side. It describes how upturned or downturned the base of the nose is relative to the lip. In MaxxLook: MaxxLook does not measure the nasolabial angle from a profile.
Philtrum
The vertical groove between the base of the nose and the top of the upper lip. Its length is sometimes compared with chin height or with the lower third of the face. In MaxxLook: MaxxLook does not measure the philtrum.
Upper-to-lower lip ratio
The visible height of the upper lip divided by that of the lower lip, taken at the center with the lips relaxed and closed. Lip position, expression and lip liner all change the reading. In MaxxLook: MaxxLook does not measure an upper-to-lower lip ratio.
Gonial angle (also called jaw angle, mandibular angle)
The angle at the back corner of the lower jaw, between the rising rear edge of the jaw and its lower border. It is properly measured from a side view or an X-ray, because the corner sits behind the visible outline of the face from the front. In MaxxLook: MaxxLook takes no geometry from its profile photos, so it does not measure the gonial angle.
Chin projection and profile convexity (also called facial convexity)
Seen from the side, chin projection is how far forward the chin sits relative to the lips and forehead, and profile convexity is how curved the profile is from forehead to nose to chin. Both need a true side view with the head level. In MaxxLook: MaxxLook takes no geometry from its profile or quarter photos, so it measures neither.
Symmetry and alignment
Symmetry compares the two sides of the face with each other rather than with anyone else. The facial symmetry guide explains why every face is a little uneven, and the free symmetry checker runs in your browser.
Facial symmetry (also called left–right symmetry)
How closely the two halves of a face match in size, height and angle. No face is perfectly symmetric, and head turn, side lighting and expression in a photo add asymmetry that is not really there. In MaxxLook: MaxxLook measures it from the front photo as left and right differences in width, height and tilt for each region, the nose’s offset from the face midline, and overall contour symmetry.
Facial midline
An imaginary vertical line that splits the face into left and right halves, usually running through the center of the forehead, the bridge and tip of the nose, the center of the lips and the chin. Symmetry readings are taken relative to it. In MaxxLook: MaxxLook uses a face midline from the front-photo mesh and reports how far the nose sits from it as one of its symmetry readings.
How scores work
A measurement only becomes a reading once it is compared with something. These terms describe that comparison; the transparency page gives the full scoring rules.
Reference range
The spread of values a measurement takes across a defined group of people, used to say whether one reading is typical, high or low for that group. It describes the group; it says nothing about which values are better. In MaxxLook: MaxxLook builds its reference ranges by running its own pipeline over the FairFace image collection (CC BY 4.0) for each sex and age group, and smile and skin readings have none, so they show exact values only.
Percentile
The share of a comparison group that falls below a given value, so the 70th percentile means 70 percent of the group sit lower. A percentile means only as much as the size and makeup of the group behind it. In MaxxLook: MaxxLook shows a percentile against other members only when at least 30 comparable analyses exist, and withholds it otherwise.
Noise floor (also called minimum detectable change)
The smallest change in a measurement that can be told apart from the variation you would get by simply retaking the same photo. A change below it is as likely to come from light, angle or compression as from the face. In MaxxLook: MaxxLook gives every test a noise floor and reports a change smaller than it as “within noise” rather than as progress.
Reference ranges are explained in more depth under where reference readings come from, and the noise floor under what can be detected over time.