Harmony & facial ratios
Deviation of IAA & JFA
1 min read · Updated October 4, 2026
The gap between your ipsilateral alar angle and your jaw frontal angle.
What it is
This is a consistency check. It compares the angle the nose and eyes make with the angle the jaw makes. The idea is that in a harmonious face the middle and lower face taper to a similar degree, so the two angles should be close.
How it's measured
It is the absolute difference, in degrees, between the ipsilateral alar angle and the jaw frontal angle. A smaller deviation means the two angles agree.
How it's read
A small gap is read as a smooth, continuous taper from the midface down to the chin. A larger gap is a descriptive sign that the lower face tapers differently from the upper. The tolerance is wide on purpose, since the two angles are taken from different parts of the face.
What affects it
Because it combines two angles, any head tilt or expression shift counts twice. A level, relaxed, front-on photo keeps the deviation honest.
Related measurements
In the same group: Facial Symmetry, Jaw Slope and Bigonial Width. The full list is on the Harmony overview.
See it on a full report
Open the sample report to see every measurement, score and highlight on a real example.