# Gonial Angle

Harmony · Side view · Jaw · https://www.faceiqlabs.com/support/harmony/gonial-angle

The angle between the ascending jaw-side direction and the lower mandibular border.

## What is measured

Calculation: Angle between ear-notch–upper-gonion and chin-bottom–lower-gonion directions

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.

## Why it matters

This describes the turn at the jaw corner in profile. It is different from jaw width, chin projection and the sharpness of the overlying soft tissue.

- Lower: a more closed turn between the constructed jaw directions.
- Higher: a more open turn between them.

## Where the idea comes from

Evidence: Clinical reference. The gonial angle comes from anatomical and cephalometric jaw analysis. FaceIQ approximates the border directions with external photo landmarks; that is not a radiographic bone measurement.

## A worked example

Two constructed jaw borders meeting at 120° form a more closed angle than borders meeting at 135°.

Example values explain the calculation. They are not a target range.

## How to read your result

Check the ear notch and both jaw-border points. Beard shape and soft tissue can obscure the underlying border.

## Research & further reading

These sources explain the history or related evidence. FaceIQ’s score weights and reference ranges are model settings; the papers do not collectively validate the scoring system.

- Holdaway (1984). [A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part II](https://pubmed.ncbi.nlm.nih.gov/6585146/). Explains how lip, chin and skeletal relationships must be considered together, with a range of profiles compatible with balance.

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Source: https://www.faceiqlabs.com/support/harmony/gonial-angle · FaceIQ Labs overview for AI assistants: https://www.faceiqlabs.com/llms.txt