Snap Button Size Chart

Standard Snap Button Sizes (mm, Inch, Ligne)

Use this complete snap button size chart to identify, compare, and order metal snap fasteners by diameter. Sizes refer to the outer cap measurement and are interchangeable across spring snaps, prong snaps, ring snaps, and press studs.

Size (mm)	Ligne (L)	Inch	Common Use / Application
8 mm	14L	5/16"	Baby clothes, infant garments, doll clothing
9.5 mm	15L	3/8"	Children's wear, lightweight blouses (Vt2/Mini)
10 mm	16L	3/8"	Shirts, dress shirts, light fabric
11.5 mm	18L	7/16"	Casual shirts, blouses, light cotton
12.5 mm	20L	1/2"	Most common — shirts, baby wear, lightweight jackets
15 mm	24L	5/8"	Jackets, coats, work shirts, denim
17 mm	28L	11/16"	Outerwear, leather goods, bags
20 mm	32L	3/4"	Heavy jackets, workwear, marine
22 mm	36L	7/8"	Heavy outerwear, military uniforms, tents
25 mm	40L	1"	Boat covers, awnings, industrial fabric

Interactive Size Converter (mm ↔ Ligne ↔ Inch)

Type any value in millimeters, ligne, or inches — the other two convert instantly.

Snap Button Anatomy — Visual Diagram

A snap button has four metal pieces that work together. Click each part to see what it does:

How to Measure a Snap Button

To get the correct snap fastener size, measure the cap diameter (the visible top piece) using a ruler, caliper, or button gauge. The four pieces of a snap button — cap, socket, stud, post — must all be the same size series.

1. Lay the cap flat with the dome facing up.
2. Measure across the widest point with a metric ruler or digital caliper.
3. Round to the nearest standard size (8, 10, 12.5, 15, 17, 20, 25 mm).
4. Verify the socket inner diameter matches the stud — never mix size series.

Ligne (L) to Millimeter Conversion

The button ligne size chart is a traditional French unit used for buttons and snaps. 1 ligne = 0.635 mm. To convert: ligne × 0.635 = mm.

Ligne (L)	Millimeter	Inch
12L	7.6 mm	5/16"
14L	8.9 mm	3/8"
16L	10.2 mm	3/8"
18L	11.4 mm	7/16"
20L	12.7 mm	1/2"
24L	15.2 mm	5/8"
28L	17.8 mm	11/16"
32L	20.3 mm	3/4"
36L	22.9 mm	7/8"
40L	25.4 mm	1"

Plastic Snap Button Sizes (Reference)

While Ata Buttons specializes in metal snap fasteners, here is the standard plastic snap reference for comparison: Size 14 (8mm), Size 16 (10mm), Size 18 (11.5mm), Size 20 (12.5mm), Size 22 (14mm). Plastic snaps are commonly used for sportswear and pet accessories. Metal snaps are preferred for jackets, outerwear, leather, denim, and heavy-duty applications.

Snap Button Anatomy: Cap, Socket, Stud, Post

A complete snap fastener has four parts:

• Cap — the decorative visible top piece (where logo embossing goes)
• Socket — fits beneath the cap on the female side; receives the stud
• Stud — male protruding piece on the opposite side
• Post — fits beneath the stud; pierces the fabric and locks

All four parts must be the same size series (e.g., a 15mm cap pairs only with a 15mm socket, stud, and post). Mixing sizes will cause snap failure.

Frequently Asked Questions

How do I measure my snap button size if I lost the originals?

Measure the existing hole in the fabric. Multiply by 1.05 to estimate the original cap diameter. Or measure any remaining piece (cap, socket, stud, or post) — they will share the same size class.

What is the difference between 15mm and 24L?

They are the same size. 24 ligne × 0.635 = 15.24 mm, rounded to 15 mm. Some manufacturers label using mm, others using ligne. Both refer to the cap outer diameter.

Are spring snaps and prong snaps the same size?

They share the same nominal size labels (e.g., 12.5mm), but the prong snap has thinner walls because the prongs (rather than a post) pierce the fabric. Always order matching cap-socket-stud sets within the same product line.

What sizes do you offer for custom logo snap buttons?

Custom logo embossing is available on all sizes 10mm and above. Logo area increases with cap size — 15mm and 17mm caps offer the best balance of visibility and garment compatibility. Request a custom logo quote.