Nasal index: the ratio of nose width to nose height
Quick facts
- Definition
- Ratio between the width of the nose and its height, usually expressed as a percentage.
- Formula
- Alar width divided by nasal height (nasion to subnasale), times 100.
- Classification
- Narrower or wider noses, according to the ranges in each reference table.
- Limit
- It does not describe profile, tip or dorsum, and it varies between populations.
The nasal index is a measure of nose proportion: it compares width with height. It is part of facial anthropometry and is used to describe the nose objectively, without relying on the eye alone.
How is it calculated?
Nasal index = (alar width ÷ nasal height) × 100.
The alar width is the distance between the most lateral points of the nostril wings. The height runs from the nasion, at the root, to the subnasale point, at the base of the columella.
Hypothetical example: a width of 35 mm and a height of 50 mm give 35 ÷ 50 × 100 = 70. A lower value indicates a relatively narrower nose, and a higher one, a wider nose. The classification ranges depend on the table and the reference population, so record which one was used.
What does the index show, and what does it not?
| Aspect | Nasal index |
|---|---|
| Width relative to height | Shows it |
| Shape of the dorsum | Does not show it |
| Tip projection | Does not show it |
| Relationship with the eyes | No, see intercanthal distance |
That is why it is a complement, never an indication. The anatomy of the nose holds important vessels, and any approach requires careful assessment. See nose anatomy for injectables.
Frequently asked questions
How do I calculate the nasal index?
Divide the width of the base of the nose (alar width) by the height of the nose, from the nasion to the subnasale, and multiply by 100. The result places the nose between narrower and wider.