SIZES & SPECS
Button Size Chart: Ligne (L) to Millimetre Conversion
Ligne (abbreviated L) is the standard unit for button diameter in the garment industry. One ligne equals 0.635 mm, so a 20L button measures 12.7 mm across. Below is the full conversion table we quote from, from 14L through 60L, together with the garment types each size normally appears on and the tolerance we hold on the diameter in production.
What Is a Ligne?
Ligne (pronounced "line", symbol L) comes from the French button trade and is still the working unit for buttons worldwide. The conversion is fixed and exact:
Because one inch is 25.4 mm and there are 40 ligne to the inch, 40 L = 25.4 mm exactly. Every other size follows from that. When a buyer specifies "20L", we read it as 12.7 mm nominal diameter — but the actual button is not machined to a single number, which is what the tolerance column below is for.
Ligne to Millimetre Conversion Table
Sizes 14L to 60L cover the overwhelming majority of garment buttons. The millimetre figure is the nominal diameter; the last column is the tolerance band we hold in production.
| Ligne (L) | Diameter (mm) | Inch (approx.) | Typical use | Production tolerance |
|---|---|---|---|---|
| 14 L | 8.9 mm | 11/32" | Babywear, shirt cuffs, fine knitwear | ±0.20 mm |
| 16 L | 10.2 mm | 13/32" | Shirts, blouses, lightweight knitwear | ±0.20 mm |
| 18 L | 11.4 mm | 15/32" | Shirts, blouses, childrenswear | ±0.20 mm |
| 20 L | 12.7 mm | 1/2" | Shirts, polo shirts, casual tops | ±0.25 mm |
| 22 L | 14.0 mm | 35/64" | Trousers, skirts, workwear | ±0.25 mm |
| 24 L | 15.2 mm | 19/32" | Trousers, jackets, denim waistbands | ±0.25 mm |
| 26 L | 16.5 mm | 5/8" | Trousers, jackets, coats | ±0.30 mm |
| 28 L | 17.8 mm | 45/64" | Jackets, blazers, denim jackets | ±0.30 mm |
| 30 L | 19.1 mm | 3/4" | Jackets, coats, outerwear | ±0.30 mm |
| 32 L | 20.3 mm | 13/16" | Coats, outerwear, denim | ±0.35 mm |
| 34 L | 21.6 mm | 27/32" | Coats, overcoats, heavy outerwear | ±0.35 mm |
| 36 L | 22.9 mm | 7/8" | Coats, overcoats, duffle coats | ±0.35 mm |
| 38 L | 24.1 mm | 15/16" | Overcoats, capes, statement outerwear | ±0.40 mm |
| 40 L | 25.4 mm | 1" | Overcoats, capes, decorative outerwear | ±0.40 mm |
| 44 L | 27.9 mm | 1-3/32" | Fashion outerwear, decorative buttons | ±0.45 mm |
| 48 L | 30.5 mm | 1-3/16" | Fashion outerwear, statement pieces | ±0.50 mm |
| 54 L | 34.3 mm | 1-11/32" | Coat fronts, decorative and trim use | ±0.55 mm |
| 60 L | 38.1 mm | 1-1/2" | Large decorative buttons, capes, covers | ±0.60 mm |
How to Measure a Button Correctly
Two buttons can look identical and measure differently, because diameter is not the only dimension that matters. Measure and record all three:
- Diameter — across the widest point of the face, flat side down on a caliper. Take three readings and use the average; moulded buttons are rarely perfectly round.
- Thickness (height) — from the face to the underside, excluding the shank. A shank button's total height is diameter-relevant only at the rim.
- Shank or hole specification — for shank buttons, the shank hole diameter and shank height; for sew-through buttons, the number of holes, hole spacing and hole diameter.
Choosing a Size for a New Garment
There is no universal rule, but the ratios below are what we see across shirting, tailoring and outerwear programmes, and they rarely need to be overridden:
| Garment | Front placket / body button | Cuff or detail button |
|---|---|---|
| Business shirt | 18 L – 20 L | 14 L – 16 L |
| Casual / polo shirt | 20 L – 24 L | 16 L – 18 L |
| Blouse | 16 L – 20 L | 14 L – 16 L |
| Trousers / chinos | 22 L – 26 L | 20 L – 22 L (back pocket, fly) |
| Jeans (waistband) | Shank or jeans button, to drawing | Rivet, to drawing |
| Jacket / blazer | 24 L – 30 L | 18 L – 22 L (sleeve vents) |
| Coat / overcoat | 30 L – 40 L | 22 L – 28 L |
Why Tolerance Matters More Than the Nominal Size
A 20L button is nominally 12.7 mm, but production runs are not physically capable of holding a single number across a moulding or die-casting cycle. The tolerance band tells you the range you will actually receive, and it matters for two reasons:
- Buttonhole fit. If your buttonhole is cut to the tight side and the button arrives at the top of its tolerance band, the garment will not fasten. We will confirm the tolerance against your buttonhole specification before production if you send it.
- Multi-colour or multi-material sets. When a garment uses the same size button in two materials — say a 20L plastic button on the front and a 20L metal button on a cuff — the two processes have different tolerances and the parts will not be dimensionally identical. We flag this at quotation stage rather than after sampling.
Non-Standard and Custom Sizes
Not every programme fits the table. Common reasons to go custom:
- A design calls for a size between two standard steps (for example 21L).
- The garment needs a matched set — front button, cuff button and a decorative trim button in three different sizes from one tooling family.
- The button must fit an existing buttonhole from a previous supplier, and the original nominal size no longer matches what is on the market.
Custom sizes are cut from a new mould, so they carry tooling cost and a sampling cycle. Lead time and MOQ for custom-moulded buttons are covered in detail in our sourcing guide.
Quick Answers
What is 20L in millimetres?
20L = 12.7 mm (1/2 inch). This is the standard front-button size for men's shirts and polo shirts.
What is 24L in millimetres?
24L = 15.2 mm (19/32 inch). Common on trousers, jackets and denim waistbands.
What is 18L in millimetres?
18L = 11.4 mm (15/32 inch). A standard shirt button size, also used on childrenswear.
How many ligne are in an inch?
Exactly 40 ligne to one inch. This is the basis of the whole conversion system.
Can you produce a size that is not on this chart?
Yes. Custom diameters are made from new tooling. Send the target diameter in millimetres and we will quote mould cost, MOQ and sampling time.
Need a quote on this specification?
Send the size, material, quantity and target date. We reply with unit price, MOQ and lead time within 24 hours — from our own factory in Ruian, Zhejiang.