Torso-to-Leg Ratio — Sitting Height and the Cormic Index
The torso-to-leg ratio is usually measured as sitting height divided by total height. It is a cleaner number than “torso length” because the landmarks are easier to repeat.
What the number means
The Cormic index is sitting height divided by height. A sitting height of 88.4 cm on a 170 cm person gives 0.52, or 52%. That means the seated head-and-trunk share is 52% of stature; the remaining 48% is the leg contribution.
leg share ≈ 1 − Cormic index
How to measure sitting height
- Sit on a flat, firm chair with your back straight and feet flat on the floor.
- Keep the head in a neutral position, looking straight ahead.
- Measure from the seat surface to the top of the head.
- Do not include the chair height or the thickness of a cushion.
Sitting height includes the head, neck and trunk. It is not the same as “torso length” measured from shoulder to crotch. The seated landmark is easier to repeat, which is why anthropometry uses it.
Reference ranges
| Population | Typical sitting-height ratio |
|---|---|
| European | ~0.52 |
| African | ~0.51 |
| Asian / Far Eastern | ~0.53–0.54 |
| Broad adult range | 0.48–0.55 |
These are population means, not individual targets. A person can sit outside the range and be perfectly typical for their own body. The value is useful for comparing torso and leg share, not for grading a body.
Use in clothing fit
A higher Cormic index means a longer torso relative to the legs. That can affect where a high-rise waistband sits, how a cropped jacket reads, and whether a longline coat ends at the intended point. A lower index means a longer leg line; the same garment can read differently. Use it with the garment’s own rise and length measurements.
Use in figure drawing
A low ratio gives a longer leg line; a high ratio gives a longer torso. Neither is “better”. In the eight-head canon, the crotch sits at the midpoint, which corresponds to a leg share of about 50%. Real bodies vary around that, and the drawing guide shows how to adjust the scaffold.
Limits
- Chair height and posture change the reading; use the same chair each time.
- Sitting height includes the head and neck, so it is not a pure torso measure.
- Population averages differ; a single band is a broad reference, not a diagnosis.
Questions
What is the Cormic index?
The Cormic index is sitting height divided by total height. It describes how much of your stature is made up of the head, neck and trunk versus the legs. A lower value means relatively longer legs.
How do I measure sitting height?
Sit on a flat chair with your back straight and feet flat. Measure from the seat surface to the top of your head, with the head in a neutral position. Do not add the chair height.
Is a lower Cormic index better?
No. It is a proportion, not a grade. Population averages differ, and a higher or lower value can be normal. The number is useful for fit and drawing, not for ranking bodies.
Sources
- Bogin & Varela-Silva (2010). Bogin, B., & Varela-Silva, M. I. (2010). Leg length, body proportion, and health: a review with a note on beauty. International Journal of Environmental Research and Public Health, 7(3), 1047–1075. https://pmc.ncbi.nlm.nih.gov/articles/PMC2872302/ Explains why leg length has no single definition: inseam, iliac height and subischial leg length give different ratios.
- Pheasant (1986) / UNU. Pheasant, S. (1986). Bodyspace: Anthropometry, Ergonomics and the Design of Work. Cited in the UNU open chapter “The effect of shape”. https://archive.unu.edu/unupress/food2/UID10E/UID10E06.HTM Sitting-height-to-stature ratios: about 0.52 European, 0.51 African, 0.53–0.54 Asian; 0.48–0.55 across populations.