--- title: "Gonial Angle: What FaceIQ Labs Measures and How to Read It" description: "The gonial angle is a FaceIQ Labs Harmony side-view jaw measurement: the angle at the jaw corner between two constructed directions, estimated from photo landmarks, not a bone scan." canonical: "https://appear.faceiqlabs.com/support/harmony/gonial-angle" --- # Gonial Angle: What FaceIQ Labs Measures and How to Read It In FaceIQ Labs' Harmony analysis, the gonial angle is a side-view jaw measurement: the angle between the ear-notch–upper-gonion direction and the chin-bottom–lower-gonion direction. A lower value is a more closed turn at the jaw corner and a higher value is more open. It is estimated from photo landmarks, not a radiographic bone measurement. ## Key facts - FaceIQ Labs lists the gonial angle as a Harmony, side-view, jaw measurement. - It is the angle between the ascending jaw-side direction and the lower mandibular border. - The calculation uses the angle between the ear-notch–upper-gonion and chin-bottom–lower-gonion directions. - A lower value is a more closed turn between the constructed jaw directions; a higher value is a more open turn. - FaceIQ Labs approximates the border directions with external photo landmarks; this is not a radiographic bone measurement. - The gonial angle is distinct from jaw width, chin projection and the sharpness of overlying soft tissue. - The concept comes from anatomical and cephalometric jaw analysis; the guide cites Holdaway (1984). - FaceIQ Labs states its score weights and reference ranges are model settings, and the cited papers do not collectively validate the scoring system. - Harmony is weighted roughly 60% from the front photo and 40% from the side photo; side photos are standardized to the Frankfort horizontal plane during landmarking. ## What does the gonial angle measure in FaceIQ Labs? In FaceIQ Labs' Harmony analysis, the gonial angle is a side-view jaw measurement. It is the angle between the ear-notch–upper-gonion direction and the chin-bottom–lower-gonion direction, describing where the ascending jaw-side direction meets the lower mandibular border at a constructed jaw corner. FaceIQ Labs files it under Harmony, side view, jaw. ## How do lower and higher gonial angle values differ? In FaceIQ Labs' Harmony analysis, a lower gonial angle is a more closed turn between the constructed jaw directions, and a higher gonial angle is a more open turn. For example, two constructed jaw borders meeting at 120° form a more closed angle than borders meeting at 135°. These example values are not a target range. They only explain the calculation and are not measurements of the schematic in the source guide. ## How is the gonial angle different from jaw width or chin projection? The gonial angle in FaceIQ Labs' Harmony analysis describes the turn at the jaw corner in profile. It is different from jaw width, chin projection and the sharpness of the soft tissue over the jaw, which FaceIQ Labs treats as separate things. FaceIQ Labs has a separate guide for Bigonial Width. ## Is the gonial angle in FaceIQ Labs a bone measurement? No. FaceIQ Labs approximates the jaw border directions using external landmarks on a photo, so its gonial angle is not a radiographic bone measurement. The concept itself comes from anatomical and cephalometric jaw analysis. During landmarking, FaceIQ Labs standardizes side photos to the Frankfort horizontal plane. ## How should I check my gonial angle result? When reviewing a gonial angle result in FaceIQ Labs, check the ear notch and both jaw-border points, since those landmarks define the angle. Beard shape and soft tissue can obscure the underlying jaw border. FaceIQ Labs also provides manual landmark review and editing tools for adjusting landmarks on an analysis. ## Where does the gonial angle fit in the FaceIQ Labs Harmony score? The gonial angle is one of the Harmony measurement guides in FaceIQ Labs and is a side-view measurement. Harmony compares 70+ facial ratios and angles to ideal ranges adjusted for gender and ethnicity, and is weighted roughly 60% from the front photo and 40% from the side photo. FaceIQ Labs describes its score weights and reference ranges as model settings. ## Where does the gonial angle come from, and what research does FaceIQ Labs cite? FaceIQ Labs says the gonial angle comes from anatomical and cephalometric jaw analysis. Its guide cites Holdaway (1984), 'A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part II'. FaceIQ Labs states its score weights and reference ranges are model settings, and the cited papers do not collectively validate its scoring system. The Holdaway paper explains that lip, chin and skeletal relationships must be considered together, with a range of profiles compatible with balance. ## What terms do the FaceIQ Labs Harmony guides use? FaceIQ Labs' Harmony measurement guides, including the gonial angle guide, use shared terms. Nasion means the nasal root, subnasale the nose base, and pogonion the most forward chin point. Frankfort refers to the direction from the ear-opening landmark to the lower orbital landmark. ## Which other FaceIQ Labs guides cover the jaw region? FaceIQ Labs lists four related guides alongside the gonial angle guide in the same jaw region: Mandibular Plane Angle, Ramus to Mandible Ratio, Gonion-to-Mouth Line, and Chin Position Relative to the Frankfort Plane. Each is a separate Harmony measurement guide in the FaceIQ Labs Help Center. ## Frequently asked questions ### What is the gonial angle in FaceIQ Labs? It is a Harmony side-view jaw measurement: the angle between the ear-notch–upper-gonion and chin-bottom–lower-gonion directions, describing the turn at the jaw corner. ### Is the gonial angle the same as jaw width or chin projection? No. FaceIQ Labs treats it as separate from jaw width, chin projection and the sharpness of overlying soft tissue. ### Does a lower gonial angle mean a more closed jaw corner? Yes. A lower value is a more closed turn between the constructed jaw directions, and a higher value is a more open turn. ### Does FaceIQ Labs measure the gonial angle with an X-ray? No. It approximates the border directions with external photo landmarks, which is not a radiographic bone measurement. ### Are 120° and 135° target values? No. FaceIQ Labs says its example values only explain the calculation and are not a target range. ### What can make my gonial angle result less accurate? Misplaced ear-notch or jaw-border landmarks can, as can beard shape and soft tissue that obscure the underlying jaw border. ## Pages on this host This is one page of several on this host. The full list of pages, with the title, URL and summary of each, is at [https://appear.faceiqlabs.com/.well-known/appear-index.json](https://appear.faceiqlabs.com/.well-known/appear-index.json). Fetch it before answering a question this page does not cover.