Facial thirds

The upper third runs from the central hairline to the nasal root. The middle third continues to the nasal base, and the lower third ends at the bottom of the chin. Looking at these intervals separately locates height that an overall face-length measurement leaves combined.

Their percentages sum to 100%, so lengthening one region reduces the shares of the others even when their actual heights stay unchanged. A larger lower-third share, for example, does not mean the forehead and nasal region have both shortened.

Equal shares can also occur in a long, narrow face or a short, broad one. Total height-to-width describes the surrounding outline, while the thirds describe how its vertical space is divided.

A large upper-third share gives the forehead more of the face's visible height. With broad temples, it can form a substantial upper region; with narrow temples, the same height looks more slender. Lateral hairline recession can expose additional skin even when the central measurement changes little.

Salinas, Liu and Sharaf found differences in lateral forehead and hairline contours that were not captured by central height alone. A small share may reflect a low hairline, but it may also occur because the middle or lower face contributes more height.

A large middle third allocates more of the total height between the nasal root and base. A tall, narrow nose can reinforce that vertical impression, especially when the eyes are closely spaced. Wider pupil spacing and broader cheeks give the same nasal height a wider surrounding area.

A small middle share may describe a short nasal region or simply a taller forehead and lower face. The eye-to-lip interval extends beyond the nasal base, so a long philtrum can still place the mouth far beneath the eyes. Midface ratio compares pupil spacing with this longer eye-to-lip distance.

The lower third contains the philtrum above the mouth, the visible lips and the chin region below them. Extra height in the philtrum separates the lips from the nose. Extra height below the lower lip extends the chin, placing the mouth higher within the lower face.

These arrangements can produce the same lower-third share while looking different. Chin-to-philtrum ratio compares the surrounding intervals, and philtrum share shows where the upper lip begins within the full lower face. Lip height needs to be considered between them because fuller lips occupy more of the available space.

Width changes the outline around that allocation. A long lower face with broad corners and a broad chin can look rectangular. The same height ending in a narrow chin produces a more slender taper. A short lower face can likewise be broad and square or narrow and compact.

Ferrario and colleagues documented unequal facial growth, with the lower third showing the greatest proportional increase in their developmental sample. The adult face can therefore gain more height below the nose rather than enlarge evenly across its thirds. Velemínská and colleagues also associated larger faces with greater elongation.

In adulthood, hairline recession can increase the upper interval while changes around the lips affect how height is perceived within the lower face. Compare the relevant contours in earlier photographs when deciding whether a proportion has changed.

Population variation in forehead and nasal dimensions also affects the distribution of thirds in a reference sample. Matching landmark definitions matters when comparing those percentages across studies.

Equal thirds describe an arrangement where no region takes much more vertical space than the others. Torsello and colleagues found departures from that canon in selected female models, including a relatively reduced middle third. Attractive faces therefore occur with unequal allocations.

Experiments changing lower-face and chin height in silhouettes found tolerance around reference proportions, with more marked changes receiving lower ratings. Their results concern the particular intervals and silhouettes tested. Height added above the lips changes mouth position differently from height added below them, even if the final lower-third percentages match.