If you've ever seen a button listed as “24L” and wondered what that means in millimeters, you're not alone. Buttons are measured in a unit called the ligne — here's the full conversion, plus the right size for every garment.
- A ligne (“L”) is the unit for button diameter. 1 ligne = 0.635 mm (1/40 inch).
- To convert, multiply ligne by 0.635 for millimeters. Example: 24L × 0.635 ≈ 15 mm.
- Common sizes: shirts 16–18L, jacket cuffs 24L, jacket fronts 32–36L, coats 36–45L.
What is a ligne?
The ligne is a French unit that has been the global standard in the button trade for over a century. One ligne equals exactly 0.635 mm, or one-fortieth of an inch. It measures the diameter of the button across its face — not the thickness, and not the shank.
Because the ligne is universal across manufacturers, a “32L” button from one mill matches a “32L” from another — which is exactly why the industry never switched to millimeters.
Button size chart: ligne to mm
| Ligne | Millimeters | Inches | Commonly used on |
|---|---|---|---|
| 14L | 9 mm | 0.35″ | Shirt cuffs, plackets, blouses |
| 16L | 10 mm | 0.40″ | Dress shirts |
| 18L | 11.5 mm | 0.45″ | Dress shirts, blouses |
| 20L | 12.5 mm | 0.50″ | Shirts, light knitwear |
| 22L | 14 mm | 0.55″ | Knitwear, vests |
| 24L | 15 mm | 0.59″ | Jacket cuffs, trousers, cardigans |
| 28L | 18 mm | 0.71″ | Trousers, jackets |
| 30L | 19 mm | 0.75″ | Jacket fronts, knitwear |
| 32L | 20 mm | 0.79″ | Suit jacket fronts |
| 34L | 21.5 mm | 0.85″ | Blazer fronts |
| 36L | 23 mm | 0.91″ | Sport coats, coats |
| 40L | 25 mm | 1.00″ | Coats, outerwear |
| 44L | 28 mm | 1.10″ | Overcoats |
| 45L | 28.5 mm | 1.12″ | Overcoats |
| 48L | 30 mm | 1.18″ | Heavy coats, statement buttons |
| 54L | 34 mm | 1.34″ | Coats, toggles, decorative |
| 60L | 38 mm | 1.50″ | Outerwear, toggles |
| 72L | 45 mm | 1.77″ | Coats, large toggles |
Values are rounded. For an exact figure, multiply ligne by 0.635 (mm) or divide millimeters by 0.635 to get ligne.
Measuring
How to measure a button
What size should you use?
| Garment | Typical size | In mm |
|---|---|---|
| Dress shirt (front) | 16–18L | 10–11.5 mm |
| Dress shirt (sleeve/placket) | 14L | 9 mm |
| Blouse | 14–18L | 9–11.5 mm |
| Suit jacket (front) | 30–34L | 19–21.5 mm |
| Suit/blazer (sleeve/cuff) | 24L | 15 mm |
| Sport coat | 32–36L | 20–23 mm |
| Trousers/pants | 24–28L | 15–18 mm |
| Cardigan/knitwear | 24–32L | 15–20 mm |
| Overcoat/topcoat | 36–45L | 23–28.5 mm |
| Jeans (tack button) | ~17–20 mm | shank tack |
| Duffle/toggle coat | 30 mm+ | toggles |
A note on materials and size
Heavier materials can carry a slightly larger size gracefully, while delicate ones look best a touch smaller. A 32L horn button anchors a blazer front; a 16L shell or mother-of-pearl button keeps a dress shirt refined; corozo sizes much like classic shirting; and jean tack buttons are sized by the finished cap in millimeters. New to attaching them? See our guide on how to sew on a button.
Premium horn, shell, and corozo by the piece or by the gross — or dyed to your exact color.