Harmony · Front view · Jaw
Lower Third Proportion
The upper portion of the lower third, from nose bottom to mouth seam, relative to the whole lower third.
What is measured
The calculation
Nose-bottom-to-mouth-seam height ÷ nose-bottom-to-chin height × 100
Front view / Measurement guide
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Why it matters
This explains where the mouth sits within the lower face. It includes the upper lip and the space above it; it is not simply chin height as a percentage of the lower third.
- Lower: the mouth seam sits closer to the nose bottom.
- Higher: the mouth seam sits farther down the lower third.
Where the idea comes from
Classical proportion
The classical lower-face subdivision compares the portion above the mouth with the portion below. FaceIQ makes that relationship explicit using its nose-bottom, mouth-seam and chin landmarks. [1]
A worked example
A nose-to-seam span of 21 units in a 64-unit lower third gives 32.8%.
Example values explain the calculation. They are not a target range and are not measurements of the schematic above.
Research & further reading
The sources below explain the history or related evidence. FaceIQ’s score weights and reference ranges are model settings; these papers do not collectively validate the scoring system.
[1] Farkas et al. · 1985
Vertical and horizontal proportions of the face: revision of neoclassical canonsTested nine traditional proportion rules against measured faces. Useful history for facial thirds and width comparisons; classical rules are not universal targets.