--- title: "Upper Lip S-Line Position: What FaceIQ Labs Measures and How to Read It" description: "FaceIQ Labs' Upper Lip S-Line Position is a side-view Harmony measurement: the upper lip's signed distance from a line running from the nose-base/tip midpoint to the soft-tissue chin." canonical: "https://appear.faceiqlabs.com/support/harmony/upper-lip-s-line-position" --- # Upper Lip S-Line Position: What FaceIQ Labs Measures and How to Read It Upper Lip S-Line Position is a FaceIQ Labs side-view Harmony measurement of the upper lip's signed perpendicular distance from a line running from the nose-base/tip midpoint to the soft-tissue chin. In FaceIQ, negative means the lip is in front of the line, positive means behind, and zero means contact. ## Key facts - Upper Lip S-Line Position is calculated as the perpendicular upper-lip distance to the S-line multiplied by the photo scale. - The S-line runs from the midpoint between the nose base and nose tip to the soft-tissue chin. - In FaceIQ, negative means the lip lies in front of the line, positive means it lies behind, and zero means contact. - It is a side-view Harmony measurement in the Lips group of FaceIQ Labs' Harmony guides. - The nasal endpoint approximates Steiner's S-line and may differ from tracing the original nasal S-curve. - FaceIQ scales photos using an assumed 190 mm hairline-to-chin height, so millimeter values are estimates, not calibrated physical measurements. - A change in chin position can change the result without the lip moving. - Worked example values are for explanation only and are not a target range. ## What does FaceIQ Labs measure for Upper Lip S-Line Position? FaceIQ Labs measures the perpendicular distance from the upper lip to the S-line and multiplies it by the photo scale. The S-line is drawn from the midpoint between the nose base and nose tip to the soft-tissue chin. It is a side-view Harmony measurement in the Lips group. In FaceIQ's guides, 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 does Upper Lip S-Line Position matter in a Harmony analysis? FaceIQ Labs uses Upper Lip S-Line Position to place the upper lip within the surrounding side profile. The result depends on the lip's position and on both reference endpoints, the nose-base/tip midpoint and the chin, so a change in chin position can change the value without the lip itself changing. ## How does FaceIQ Labs read negative and positive Upper Lip S-Line values? - Negative: the upper lip lies in front of the S-line. - Positive: the upper lip lies behind the S-line. - Zero: the upper lip is in contact with the S-line. - This sign convention describes FaceIQ's result. The FaceIQ Labs guide does not say whether negative or positive values are better or worse. ## Where does the S-line concept in FaceIQ Labs come from? The S-line belongs to Steiner's soft-tissue profile analysis. FaceIQ Labs adapts it by approximating the nasal endpoint as the midpoint between the nose base and nose tip. FaceIQ notes that this construction may differ from tracing the original nasal S-curve. ## What does a worked example of Upper Lip S-Line Position look like? In FaceIQ Labs' example, an upper lip estimated 2 mm behind the S-line reads +2 mm. Moving it onto that unchanged line gives zero, and a lip 1 mm in front gives −1 mm. These values explain the calculation only; they are not a target range or a measurement of the guide's schematic. ## Why are FaceIQ Labs' Upper Lip S-Line millimeter values approximate? FaceIQ Labs scales each photo using an assumed 190 mm hairline-to-chin height, so the millimeter values are estimates rather than calibrated physical measurements. A midpoint-based S-line is also an approximation. Lip posture and movement of either endpoint change the distance, and the measure does not isolate tooth position. ## What research does FaceIQ Labs cite for the S-line, and what are its limits? FaceIQ Labs cites Buschang, Fretty & Campbell (2011), which compared five lip reference lines, including Steiner's S-line, in 79 orthodontic patients. It found that moving reference points can make a lip appear to move backward even when it moves forward. FaceIQ states that its score weights and reference ranges are model settings, and that the papers do not collectively validate its scoring system. ## What related side-view lip and chin measurements does FaceIQ Labs have? - Lower Lip S-Line Position - Lower Lip E-Line Position - Upper Lip E-Line Position - Lower Lip Burstone Line - Upper Lip Burstone Line - Holdaway H Line - Mentolabial Angle ## Frequently asked questions ### Is a negative Upper Lip S-Line value worse than a positive one? The FaceIQ Labs guide does not say so. It defines only the sign convention: negative means the lip is in front of the line, positive means behind, and zero means contact. ### Are the millimeter values for Upper Lip S-Line Position exact? No. FaceIQ Labs scales photos using an assumed 190 mm hairline-to-chin height, so the millimeter values are estimates, not calibrated physical measurements. ### Does chin position affect the Upper Lip S-Line Position reading? Yes. The S-line ends at the soft-tissue chin, so a change in chin position can change the result even if the upper lip has not moved. ### What is the S-line based on? It comes from Steiner's soft-tissue profile analysis. FaceIQ Labs approximates the nasal endpoint as the midpoint between nose base and tip, which may differ from the original nasal S-curve. ### Is Upper Lip S-Line Position part of the Harmony pillar? Yes. It is a side-view measurement in the Lips group of FaceIQ Labs' Harmony guides, which cover facial ratios and angles. ## Pages on this host This is one page of several on this host. 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