Upper-to-Lower Lip Ratio
The lip ratio is the height of the upper lip vermillion compared to the lower lip — a key proportion in lip aesthetics.
Definition
The upper-to-lower lip ratio compares the vertical height of the upper lip vermillion (the visible red border) to the lower lip vermillion. The classical aesthetic ideal is roughly 1:1.6 (upper to lower), meaning the lower lip is about 60% taller than the upper. Some sources advocate a tighter 1:1.5 or 1:2 ratio. Across age and gender, the lower lip is almost always taller than the upper, but the magnitude of the difference is what defines lip proportion. Ratios closer to 1:1 produce a balanced, pillowy appearance; ratios approaching 1:2.5 read as a strongly bottom-weighted lip. The ratio is influenced by lip filler distribution, age (upper lip thins faster), and natural genetic variation.
Why it matters
Lip ratio is one of the most-modified aesthetic proportions in cosmetic medicine because it is highly visible in photos and easy to adjust with hyaluronic acid filler. A balanced 1:1.6 ratio is widely considered ideal for women, while men typically prefer slightly thinner overall lips with a similar proportional balance. Mistakes in filler distribution — adding volume only to the upper lip, for example — produce the recognizable "filler face" effect by inverting the natural ratio.
How AI measures it
AI traces the upper and lower lip vermillion borders, measures the vertical height of each at the central point (philtral midline), and computes the ratio. Some tools also evaluate the ratio at the lateral commissures (corners) to detect uneven volume distribution.
Test your upper-to-lower lip ratio
Get your own upper-to-lower lip ratio score in under 10 seconds. AI-graded from a single photo.
Frequently asked questions
What is the perfect lip ratio?
The most cited ideal is 1:1.6 (upper to lower), matching phi. Anywhere from 1:1.4 to 1:1.8 is generally considered attractive depending on cultural context.
How do you fix an unbalanced lip ratio?
Lip filler placed selectively — adding volume to the smaller lip — restores balance. Skilled injectors target specific regions rather than treating both lips equally.
Does lip ratio change with age?
Yes — the upper lip thins faster than the lower lip with age, increasing the ratio (upper becomes proportionally smaller). Lip lift surgery and filler can restore youthful proportions.