Guide
Lash curls, diameters, and lengths explained
What J, B, C, CC, D, L, and M curls do, how diameter changes the look and the weight, and how artists choose lengths.
Published · 6 min read
Every lash extension is described by three numbers and a letter: its curl, its diameter, and its length. Together they decide how a set looks and how it wears.
Curl
Curl letters describe how much the extension bends from its base. The naming is broadly consistent across brands, though the exact angle varies from one manufacturer to another.
| Curl | What it does |
|---|---|
| J | The most subtle curl, close to a natural lash with little lift. |
| B | A soft, natural curl with slightly more lift than J. |
| C | The most common all-round curl, a visible lift that still reads as natural. |
| CC | Between C and D, more lift than C without the drama of D. |
| D | A strong curl for a lifted, dramatic look. |
| L | A flat base with a sharp lift, often chosen for hooded or downturned eyes and straight natural lashes. |
| M | Similar to L with a more pronounced upward curl. |
Diameter
Diameter is the thickness of a single extension in millimeters. Thinner extensions are lighter, so more of them can be grouped into a fan on one natural lash. Thicker extensions are used singly.
- 0.03 to 0.07 mm: volume and mega volume fans, several extensions per natural lash.
- 0.10 to 0.12 mm: light classic or hybrid work.
- 0.15 mm: a common classic diameter, one extension per natural lash.
- 0.18 mm and above: heavier classic lashes, used less often today because of the weight.
Length
Lengths typically run from about 6 mm at the inner corner to 15 mm or more at the longest point of a dramatic set. Many artists follow the rule of thumb that an extension should not be much longer than the natural lash it is attached to, because excess length adds leverage and weight that can stress the natural lash.
A good map balances all three. A client with fine natural lashes will usually get a lighter diameter and shorter lengths than the same style on a client with strong lashes, even if the curl and the length profile are identical.
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