Button Sizes Explained: Ligne Chart, Materials and How to Choose

Buttons are one of the few components still specified in a unit almost nobody outside the trade can convert in their head. A button listed as “24L” gives no immediate sense of scale to anyone but a trim buyer or a pattern maker — and getting it wrong means every buttonhole on the garment is wrong too.

This guide covers the ligne system, the full conversion table, the materials actually in commercial use, and what belongs on a purchase order.

The ligne (French for “line”, abbreviated L) is the unit traditionally used across the global button trade to express button diameter.

1 ligne = 0.635 mm = 1/40 inch. Therefore 40 L = 1 inch.

Conversions:

• Ligne → mm: multiply by 0.635
• mm → ligne: divide by 0.635

Example: 24 L × 0.635 = 15.24 mm.

The unit dates from 18th-century France and has been standard in the trade for over a century. The reason the industry never fully migrated to millimetres is simply that the conversion is consistent across manufacturers: a 32 L button from one mill matches a 32 L from another.

What gets measured: the diameter across the face of the cap. Not the thickness, and not the shank.

1. Lay the button face up on a flat surface (or hold it in a caliper).
2. Measure straight across the widest point of the cap. For oval or novelty shapes, measure the longest dimension. For a shank button, measure the cap only and ignore the shank.
3. Divide the millimetre figure by 0.635, or read it off the chart below.

If you are replacing a lost button, always measure one of the surviving buttons from the same garment rather than trusting the pattern.

Always confirm against your own pattern — these are working conventions, not rules.

A buttonhole must be cut to the button’s diameter plus an allowance for thickness, typically 2–3 mm. Working backwards:

• A finished 22 mm buttonhole suits roughly a 19–20 mm (30–32 L) button.
• A finished 18 mm buttonhole suits roughly a 15–16 mm (24 L) button.

Going more than a couple of millimetres under leaves buttons slipping open. Going over means they will not pass through at all.

Buttons are ordered in dozens, grosses and great grosses:

Ordering example: 3,456 shirts needing 6 buttons each = 20,736 buttons = 12 GG. In practice add a minimum of ~3 % overage to cover losses, defects and shortage-in-wear replacements.

The workhorse of the industry. Cast into sheets or rods and turned on automatic lathes.

• Takes dye well, including pearlescent and iridescent finishes
• Good impact resistance and good dimensional stability
• Can be laser-engraved; can be tumbled to matte, satin or high gloss
• Generally the safest all-round choice for durability through laundering

Harder and denser than polyester with a characteristically cool, ceramic-like feel. Very common on quality shirting.

• Excellent hardness and scratch resistance, takes a high polish
• More prone to damage from high heat and steam pressing, and can craze with some finishing processes
• Request confirmation that the finish is compatible with your laundry or dry-cleaning process before committing

Genuine natural shell — freshwater, river shell, or premium blacklip. Each button is unique.

• Premium appearance; no two are identical, which is part of the appeal
• Naturally iridescent; the nacre layer can be polished or left matt
• Shell requires care: it is attacked by harsh chemical processes, so confirm compatibility with your dry-cleaning solvent and specify natural variation tolerances up front

The dried nut of the tagua palm. A sustainable premium alternative increasingly used in place of horn or ivory.

• Warm, hard-figured surface; takes dye beautifully
• Traceable natural and renewable — increasingly specified by sustainability programmes
• Naturally variable in tone, which should be expected and priced

Rustic, lightweight, laser-able. Popular in resortwear and sustainable collections. Expect natural grain variation and check durability through wash cycles.

Brass, zamak (zinc alloy) or stainless steel, usually plated. Mostly used on denim and outerwear.

• High durability and strong brandable surface
• Watch for plating compliance: metal articles in prolonged contact with skin must be checked against REACH Annex XVII Entry 27 (nickel release limits) for the EU market
• Weight matters — metal buttons change the hang of a light fabric

Fabric-covered (self-cover kits or factory-covered), leather-covered, and 2-component constructions combining a metal rim with a resin centre.

Understanding the process explains most of the defects buyers complain about.

1. Casting — unsaturated polyester resin with catalyst and pigment is cast into sheets or rods and cured.
2. Cutting / turning — blanks are cut from sheet, then turned to the final profile on automatic lathes. This sets the face shape, thickness and back profile.
3. Drilling — holes are drilled; hole spacing and centring tolerance are set here and are a common source of visible defects.
4. Polishing — barrel or vibratory polishing with wood or ceramic media develops the surface finish. This step largely determines gloss consistency.
5. Dyeing or finishing — either mass-pigmented during casting or dyed afterwards, depending on colour depth required.
6. Engraving — laser engraving for logos or patterns.
7. Sorting and inspection — including visual grading for surface defects and colour consistency.

Commonly requested checks and referenced methods:

Results are normally quoted on the 1–5 grey scale used across the ISO 105 series, sometimes expressed to one decimal place.

Note on attachment strength: while button pull-off strength is critical in childrenswear, there is no single universal standard. Most brands specify an in-house pull test at a defined newton value. Put the requirement and the method in the purchase order rather than assuming it is covered.

1. Size in ligne (and the mm equivalent)
2. Material — resin, urea, shell, corozo, metal
3. Style and holes — 2-hole / 4-hole / shank, plus hole spacing
4. Thickness / gauge
5. Colour reference — a recognised textile colour standard code, plus a signed physical reference for the defect review standard
6. Finish — matte, satin, gloss, or special effect
7. Quantity and packing unit — gross or GG, plus agreed overage
8. Tolerance — dimensional and colour
9. Care compatibility — state the laundry or dry-cleaning process the button must survive
10. Applicable test requirements and acceptance criteria

Ligne (written L) is the button-trade unit of diameter. One ligne is exactly 0.635 mm, or one fortieth of an inch. Forty ligne equals one inch.

Multiply ligne by 0.635. To go the other way, divide millimetres by 0.635.

Dress shirts typically run 14L–18L on the placket and collar, with 24L on cuffs. Always verify against your pattern.

Usually heat. Urea buttons are more sensitive to high heat and steam than polyester. Check your finishing temperatures and confirm material compatibility with the finisher’s process before bulk production.

Polyester resin is the durable all-rounder. Urea gives a harder, cooler feel and a finer polish, with more heat sensitivity. Mother of pearl is a premium choice with natural variation and more care-restriction downstream.

Rarely accurately — colour rendering varies too much. Send a physical sample, or at minimum a high-resolution image alongside a precise measurement and the ligne figure if known.

Formulae and conversion values in this guide are industry reference figures. Always approve a physical reference sample against your own pattern and finishing process before bulk ordering.

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