What the term actually describes
The Ricketts E-line (esthetic line, sometimes "E-plane") is a straight reference line drawn in side profile between two points:
- Nasal tip — the most forward point of the nose.
- Soft-tissue chin point — the most forward point of the chin.
Lip projection is then read as a distance — how far the upper and lower lip sit in front of or behind that line — not as an angle like nasolabial angle or gonial angle. It requires a genuine side-profile view, the same camera-setup limitation both of those pages cover.
Where it comes from
The E-line was introduced by Robert M. Ricketts, an American orthodontist, as part of a cephalometric analysis system published in the late 1950s and refined through the 1960s for orthodontic and orthognathic-surgery treatment planning. It remains one of the most-cited soft-tissue profile references in that clinical literature today — a diagnostic tool built for treatment planning, not a beauty scale.
Why the quoted "ideal" doesn't generalize
Ricketts' original reference values — commonly cited as the upper lip sitting roughly 4 to 6 millimeters behind the line and the lower lip roughly 2 to 4 millimeters behind it — came from Caucasian samples. Later peer-reviewed research testing lip-position preference across different ethnic backgrounds found that population norm doesn't hold universally:
- Studies comparing perceived facial-profile attractiveness across ethnic backgrounds found African and East Asian faces average more forward lip position relative to the E-line than Ricketts' original Caucasian-derived figures, without a corresponding drop in perceived attractiveness.
- The measurement is also sensitive to its own endpoints — nose or chin projection shifts the whole reference line, so the same lips can read as more or less "behind the line" depending on unrelated changes elsewhere in the profile.
That's the same caution this site applies to any single quoted ideal figure: a published reference range describes what one study sample averaged, not a universal target, the same point made about the golden ratio face template and the sex-specific ranges on the nasolabial angle page.
Where this fits next to what Mogalytics actually reads
Mogalytics does not compute or display a separate E-line reading. Its six-measurement composite reads live from a front-facing camera feed, and the closest measurement in the same lower-face family is:
- Jaw ratio — jaw height relative to face height, read frontally rather than as profile projection.
Jaw ratio and the E-line both describe the lower face, but they're not the same measurement — one is a frontal height proportion, the other is a profile projection distance anchored to the nose and chin. Mogalytics makes no claim of parity between the two, or with any clinical cephalometric analysis.
Related reads
The E-line sits alongside the other side-profile-only terms this site covers, plus the closest of the six live measurements. If you're auditing the rest:
- Jaw ratio — the closest camera-read analog, sensitive to chin pitch rather than profile projection.
- Gonial angle — another side-profile-only term Mogalytics doesn't compute directly.
- Nasolabial angle — another side-profile-only term, also anchored near the nose.
- Chin-to-philtrum ratio — a different lower-face ratio in the same jaw family, read frontally.
- Golden ratio face — another proportion template whose population-specific norms don't generalize universally.
- SNA/SNB angle — a related skeletal-projection angle, but one that requires an actual X-ray rather than just a photo.