Three Ratios · Deviation From 0.33

Face thirds calculator

RealSmile Research Team · Facial Analysis Specialists
Updated May 19, 2026
Based on 5 peer-reviewed sources
→ See our methodology

Upper, middle, lower. Three ratios. Deviation from the 0.33 published reference and the dominant imbalance named.

Ratios first, score second. The calculator returns the raw geometry so the imbalance is auditable, not impressionistic.

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The three ratios and what they measure

Upper third. Hairline to glabella (between the brows). The reference range is 0.30 to 0.36 of total face length. Above 0.36 reads as tall forehead; below 0.30 reads as compressed forehead.

Middle third. Glabella to subnasale (base of the nose). The reference range is 0.30 to 0.36. Above 0.36 reads as long midface; below 0.30 reads as compressed midface. This is the most structurally constrained third.

Lower third. Subnasale to chin tip. The reference range is 0.30 to 0.36. Above 0.36 reads as long lower face or long chin; below 0.30 reads as compressed or recessed chin.

Deviation summary. The calculator reports each third\'s deviation from the 0.33 reference and names the dominant imbalance category. A face with all three deviations under 0.02 is balanced. A face with one deviation above 0.05 has a noticeable imbalance in that direction.

The six imbalance categories

Balanced

All three deviations under 0.02. Reads as harmonious. Most flexible base for grooming and hairstyle choices.

Long upper third

Upper third deviation above 0.05. Reads as tall forehead. Fringe, slight forward hair, or fuller brow line balances visually.

Long middle third

Middle third deviation above 0.05. Less common. Reads as long midface. Cheekbone-emphasizing grooming and brow positioning help balance.

Long lower third

Lower third deviation above 0.05. Reads as long chin or long lower face. The largest single contributor to harmonious-to-imbalanced shift in rating studies.

Compressed upper third

Upper third deviation below -0.05. Reads as low hairline. Slicked-back styles or higher brow line opens the upper third visually.

Compressed lower third

Lower third deviation below -0.05. Reads as recessed chin or compressed lower face. Beard length or chin contouring extend the visible lower third.

How to balance imbalance visually

The structural thirds do not change in adults. What changes is the visible boundary between thirds. Three boundaries are adjustable. The hairline boundary (top of the upper third) shifts with hairstyle: a fringe lowers it by 1 to 3 centimeters, slicked-back styles raise it. The brow line (between upper and middle) shifts with brow shaping: a higher brow line moves the boundary up by 5 to 10 millimeters; a fuller, lower brow line moves it down.

The lower boundary of the middle third (the subnasale) is structurally fixed. The lower boundary of the lower third (chin tip) is structurally fixed but the visible lower third extends with beard length. A 1 to 2 centimeter beard adds visible lower-third height; clean shaven reveals the structural minimum.

Honest limits

Face thirds calculator FAQ

What are the face thirds and why do they matter?+
The face is conventionally divided into three vertical thirds: upper (hairline to glabella, the central brow ridge point), middle (glabella to subnasale, the base of the nose), and lower (subnasale to chin tip). In faces consistently rated as harmonious in the published research, the three thirds sit at approximately equal heights — each at 0.30 to 0.36 of total face length. Deviation from the 0.33 reference (the perfect equal third) is one of the inputs into the larger facial-harmony signal that drives attractiveness ratings (Perrett, Lee, Penton-Voak et al., 1998).
How does the calculator measure my face thirds?+
The calculator uses three landmark points: the hairline (top boundary), the glabella (between the brows, the boundary between upper and middle), the subnasale (base of the nose, between middle and lower), and the chin tip (bottom boundary). The vertical distance between each pair gives the height of that third, divided by total face length. The calculator returns the three ratios, their deviation from 0.33, and identifies the dominant imbalance (long upper third, long middle, long lower, compressed upper, compressed middle, compressed lower, or balanced).
What counts as balanced face thirds?+
On the published norms, each third sitting at 0.30 to 0.36 of total face length is the reference band for balanced thirds. The deviation from 0.33 is typically reported in absolute terms: under 0.02 deviation across all three is balanced; 0.02 to 0.05 deviation is mild imbalance; above 0.05 deviation is noticeable imbalance. The calculator returns the exact deviation for each third so the imbalance is auditable rather than impressionistic. Many real faces are mildly imbalanced; the threshold for "noticeable to raters" varies by which third deviates and by the surrounding face shape.
How does this differ from the facial thirds test on the site?+
The facial thirds test focuses on returning a single composite score and ranking your face thirds against the reference band. The face thirds calculator focuses on returning the three raw ratio values with the deviation from 0.33 made explicit, the dominant imbalance category named, and the geometry exposed for verification. The two tools share the same underlying landmark measurement but target different presentation: the test is score-first, the calculator is ratio-first. Most users benefit from running the calculator once to see the underlying numbers and the test as a periodic re-check.
Which third deviation matters most for attractiveness?+
On the published rating research, a noticeably long lower third has the strongest effect on reducing attractiveness ratings, followed by a noticeably long upper third, then a noticeably compressed middle third. Long upper third reads as "high forehead." Long lower third reads as "long chin" or "long lower face." Compressed middle third reduces perceived midface volume and reads as flat. The mechanism is that the lower and upper thirds are the most variable across individuals; the middle third is more constrained by orbital anatomy. The dominant imbalance category in the calculator output points to which third is the largest contributor to deviation from balance.
Can I change my face thirds?+
Bone structure (frontal bone height, midface depth, mandibular length) does not change in adults. The three thirds are structurally fixed. What changes the perceived thirds are three levers. First, hairstyle: a fringe lowers the apparent hairline and reduces the upper third by 0.02 to 0.05; a slicked-back style raises it and adds to the upper third. Second, brow shaping: a lower, fuller brow line reduces the apparent middle-to-upper boundary; a higher, thinner brow raises it. Third, facial hair: a fuller beard extends the apparent lower third; clean-shaven shortens it. The structural thirds do not move; the visible boundaries move.
Why do the thirds look different at different angles?+
Photo angle changes the apparent height of each third by a measurable amount. A camera above eye level extends the apparent upper third (the "long forehead selfie"). A camera below eye level extends the lower third. Even a slight head tilt of 5 to 8 degrees can shift the apparent ratios enough to misread one of the thirds as "long" when it is actually balanced. The calculator normalizes for head pose using facial landmark geometry, but a clean straight-on photo is still the best input. Casual mirror or selfie comparisons should not be used for self-diagnosis on thirds.
What does the $14.99 PDF unlock for face thirds?+
The free calculator returns the three ratio values, deviation from 0.33, and dominant imbalance category. The $14.99 report adds a written interpretation of how your specific imbalance interacts with your face shape and lower-third metrics, ranked hairstyle and grooming picks that visually balance your specific deviation, the comparison against the 16 other metrics in context, and a 30-day action plan for the visible levers that produce the largest balance improvement on your specific configuration.

Three ratios. One deviation report. Visual rebalancing picks for your specific imbalance.

Unlock the thirds report.

$14.99 unlocks the full 17-metric PDF: three ratios with deviations, dominant imbalance interpretation, ranked hairstyle and grooming picks, and 30-day action plan.

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Free, instant, private. Three ratios, deviation from 0.33, dominant imbalance — plus 14 more metrics.

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