Face shape guide
A square face has a jaw nearly as wide as the cheekbones, a length close to its width, and a jawline with a visible corner below the ear.

How to tell
What the detector scores
Bands are the ones the Face Shape Detector uses on uploaded photos; width is measured at the cheekbones, forehead at the temples, length from an estimated hairline to the chin.
Measure yours
Upload a straight-on photo. 478 landmarks, five readings, a score against all six shapes. Runs in your browser, nothing uploaded.
Often confused with

Round
Same width, no corner. Round scores on a jaw angle over 125° with a curved jaw and a jaw : face width over 0.78. Square needs over 0.83 and a corner in the 118° to 128° band.
Read the round guide →

Oblong
The rectangle question. Oblong is long and narrow-jawed: a length : width over 1.55 and a jaw angle under 108°. Square is under 1.45 with a jaw angle of 118° to 128°.
Read the oblong guide →
What fits
Conventional advice, stated in terms of the ratios above: frames and volume either add width where the face is narrow or add length where it is wide.
Bone vs soft tissue
Face shape is mostly bone. The distance from the hairline to the chin, the width across the cheekbones and the width at the temples are set by the skull and do not move. The jaw readings, the jaw : face width and the jaw angle, sit under soft tissue: fluid, fat and the masseter all change them by a few points, which is enough to move a face across a shape border.
The corner is bone: the angle at the gonion is the shape of the mandible and does not change without surgery. What soft tissue does is exaggerate or blur it. The masseter sits directly over the jaw corner, so a bulky, tight masseter from clenching or gum chewing widens the jaw : face ratio further, while a relaxed one narrows it by a few points. Fluid does the opposite and rounds the corner off, which is why a square face can read round after a bad night.
FAQ
No shape is. Square gets called strong in men's styling guides and angular in women's, which are descriptions of the same jaw ratio with different adjectives attached. The detector reports the ratio; the adjective is yours.
The jaw corner is bone and stays. The jaw : face ratio moves a few points with masseter bulk and fluid, so a square face at 0.84 can read as a wide oval at 0.80 on a lean, low-salt day. It does not become round, because the corner is still there.
Square borders round (same width, softer angle) and oval (a narrower jaw, 0.74 to 0.78). A jaw angle between 125° and 128° scores for both square and round; a jaw : face width between 0.80 and 0.83 earns partial credit for square while still inside oval's partial band. The overlay shows the jaw line: look for the corner.
A beard is the biggest single factor for a square reading. A full beard hides the jaw corner, and a beard that spreads below the jaw widens the lower-jaw reading. Hair over the temples narrows the forehead reading and can push the result toward diamond. Photograph with the jawline and temples visible.
Other face shapes
Canthal tilt, jaw width, midface ratio, symmetry, skin, and a 3D model of your face, each against its ideal band, bone vs trainable, and a plan.