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Button ligne explained
What a button ligne is, and how to convert ligne to millimeters and inches.
Button cards still use ligne (often written Ligne or L), a French length unit kept by the notions trade. In modern sewing it is defined as 1/40 of an international inch.
The exact size
1 ligne = 1/40 inch = 0.635 mm = 0.0635 cm. That is the button ligne (法分), not the older Paris line used for type. A 24-ligne coat button is 24 × 0.635 = 15.24 mm across.
How makers use it
Shirt buttons cluster around 16–18 ligne (about 10–11.5 mm). Jacket fronts are often 24–28 ligne. Overcoats go to 32–36 ligne. If a pattern says “3/4 in buttons”, that is 30 ligne (0.75 × 40).
Conversion table
| Ligne | mm | inch | Typical use |
|---|---|---|---|
| 14 | 8.89 | 0.350 | Baby, small shirt |
| 16 | 10.16 | 0.400 | Shirt |
| 18 | 11.43 | 0.450 | Shirt, blouse |
| 20 | 12.70 | 0.500 | Light jacket |
| 24 | 15.24 | 0.600 | Jacket |
| 28 | 17.78 | 0.700 | Coat |
| 32 | 20.32 | 0.800 | Overcoat |
| 40 | 25.40 | 1.000 | Statement / 1 inch |
Yarn note
Button size is length. Thread thickness is linear density: 9 denier = 1 tex. Do not mix ligne with denier on a spec sheet.