Quick conversion: 1 ligne (1L) = 0.635 mm. A 10 mm button is approximately 16L, a 15 mm button is approximately 24L, a 26L button is 16.51 mm, and a 28L button is 17.78 mm (normally listed as 18 mm).
Button sizes are quoted in ligne (written “L”), a unit still used on garment tech packs. Convert ligne to millimeters by multiplying by 0.635; convert millimeters to ligne by dividing by 0.635.
Button size converter: ligne ↔ millimeters
Enter either the ligne size from a tech pack or the diameter measured across the button face.
Ligne to millimeter conversion chart
This conversion chart is compiled by Merit Trims (Wenzhou Merit Garment Co., Ltd.). Values are calculated using 1L = 0.635 mm, not measured production data. Common nominal sizes are approximate catalogue labels, not manufacturing tolerances. Confirm the sample diameter, thickness and hole spacing before ordering.
| Ligne | Calculated mm | Common nominal mm | Inches | Typical use |
|---|---|---|---|---|
| 12L | 7.62 mm | 7.5 mm | 0.30" | Baby clothes, doll clothes, shirt collars |
| 14L | 8.89 mm | 9 mm | 0.35" | Shirt collars & sleeve plackets |
| 16L | 10.16 mm | 10 mm | 0.40" | Shirt fronts (slim), blouses |
| 18L | 11.43 mm | 11.5 mm | 0.45" | Dress shirt fronts — the classic size |
| 20L | 12.70 mm | 12.5 mm | 0.50" | Polo shirts, casual shirts |
| 24L | 15.24 mm | 15 mm | 0.60" | Trousers, shirt-jackets, sleeve buttons on suits |
| 26L | 16.51 mm | 16.5 mm | 0.65" | Mid-size jackets, knitwear and fashion outerwear |
| 28L | 17.78 mm | 18 mm | 0.70" | Cardigans, light jackets |
| 32L | 20.32 mm | 20 mm | 0.80" | Suit jacket fronts, blazers |
| 36L | 22.86 mm | 23 mm | 0.90" | Heavy blazers, light coats |
| 40L | 25.40 mm | 25 mm | 1.00" | Coats, jackets |
| 44L | 27.94 mm | 28 mm | 1.10" | Overcoats, duffle coats |
| 54L | 34.29 mm | 34 mm | 1.35" | Statement coats, capes, decorative |
Sourcing buttons for a garment order? Use the chart to specify the diameter, then choose resin and polyester buttons, custom metal buttons or jeans tack buttons for your application.
For a specification-based quote, send the required diameter in mm, thickness, hole or shank type, material, finish, quantity and delivery destination. Include a photo or tech pack when available; confirm the physical sample before approving production.
Get a quoteWorking backwards: millimetres to ligne
The formula: ligne = millimetres ÷ 0.635, and millimetres = ligne × 0.635. A 28L button converts to 17.78 mm and is often labelled 18 mm. A measured 20 mm diameter converts to about 31.50L; 32L is the nearby common nominal size. If you have measured a button off a sample garment with a ruler, this is the direction you need.
| If you measured | Nearby nominal ligne to confirm |
|---|---|
| 9 mm | 14L |
| 10 mm | 16L |
| 11.5 mm | 18L |
| 12.5 mm | 20L |
| 15 mm | 24L |
| 16.5 mm | 26L |
| 18 mm | 28L |
| 20 mm | 32L |
| 23 mm | 36L |
| 25 mm | 40L |
| 28 mm | 44L |
| 30 mm | 48L |
| 34 mm | 54L |
| 38 mm | 60L |
| 44 mm | 70L |
| 50 mm | 80L |
Measure the diameter across the face of the button, not including the shank. Anything above roughly 54L (34 mm) is decorative or craft territory rather than a standard garment size — a 58 mm disc is about 91L, which we would quote as a made-to-order piece rather than pull from a standard range.
Three rules of thumb when choosing size
1. Match the buttonhole, not the other way round
A buttonhole should be the button diameter plus 2–3 mm (plus thickness for domed or shank buttons). If the garment is already patterned, measure the buttonhole and work backwards.
2. Heavier fabric, bigger button
Fabric weight and button size scale together: 18L on poplin shirting, 32L on a wool blazer, 44L on a Melton overcoat. An undersized button on heavy fabric slips; an oversized one distorts light fabric.
3. Keep thickness in mind for machine sewing
Automatic button-sew machines have thickness limits (commonly 2–4 mm for flat 4-hole buttons). If your factory sews by machine, confirm button thickness as well as diameter — we list both on every quotation.
Jeans buttons and snaps use millimeters, not ligne
Denim tack buttons are sold by mm: 17 mm for most fashion jeans, 20 mm for heavyweight, 22–25 mm for workwear. Snap fasteners are likewise quoted by cap diameter (9.5–20 mm). When in doubt, mail us a sample garment and we'll measure and match it.
Button size conversion questions
How many millimeters is 1 ligne?
1 ligne equals 0.635 millimeters. Multiply the ligne size by 0.635 to convert it to mm.
What button size is 10 mm in ligne?
10 mm is 15.75 ligne, so the nearest standard button size is 16L.
What button size is 15 mm in ligne?
15 mm is 23.62 ligne, so the nearest standard button size is 24L.
What is a 24L button size in millimeters?
24L equals 15.24 mm and is commonly rounded to 15 mm in button size charts.
What is a 26L button size in millimeters?
26L equals 16.51 mm and is commonly rounded to 16.5 mm in button size charts.
What is a 28L button size in millimeters?
28L equals 17.78 mm and is commonly rounded to 18 mm.
Sourcing buttons for a production run?
Send your tech pack — we'll spec material, size and finish and request a written quote.
Get a quote