Buttons
Trims & Care · 8 specs
Direct Answer
Button sizing is globally standardized using the French Ligne scale (symbol 'L'), where 1 Ligne equals exactly 0.635 mm (1/40 inch or 0.025 in). Sized from 14L (collar button-downs) and 18L (shirt plackets) to 32L (suit coat fronts) and 40L (overcoats), the scale determines standard buttonhole cutting lengths.
Source: ASTM D5171-15 / International Ligne Button Standards · Last reviewed Aug 28, 2026
Specs
| Governing Standards | ASTM D5171 / Traditional Ligne Standard |
| Base Unit Definition | 1 Ligne (1L) = 0.635 mm = 1/40 inch (0.025") |
| 14L Shirt Collar / Gauntlet | 8.89 mm (0.350") | Button-down collars and sleeve placket gauntlets |
| 16L Shirt Cuff | 10.16 mm (0.400") | Dress shirt sleeve cuffs |
| 18L Standard Shirt Front | 11.43 mm (0.450") | Dress shirt center front placket buttons |
| 24L Suit Sleeve | 15.24 mm (0.600") | Tailored suit jacket sleeve cuffs and formal vests |
| 30L / 32L Suit Front | 19.05 / 20.32 mm (0.75 / 0.80") | Suit jacket and blazer front closures |
| 40L Overcoat | 25.40 mm (1.000") | Heavy trench coats, pea coats, and wool overcoats |
Button Ligne Sizing Chart (14L to 45L)
| Ligne Size | Diameter (mm) | Diameter (Inches) | Standard Garment Application |
|---|---|---|---|
| 14L | 8.89 mm | 0.35" (7/20") | Button-down shirt collars, sleeve gauntlets |
| 16L | 10.16 mm | 0.40" (2/5") | Standard dress shirt cuffs |
| 18L | 11.43 mm | 0.45" (9/20") | Standard dress shirt front placket |
| 20L | 12.70 mm | 0.50" (1/2") | Casual shirts, children's clothing |
| 24L | 15.24 mm | 0.60" (3/5") | Suit jacket sleeve cuffs, formal vests |
| 30L | 19.05 mm | 0.75" (3/4") | Casual blazers, trouser waistbands |
| 32L | 20.32 mm | 0.80" (4/5") | Standard suit jacket front closures |
| 36L | 22.86 mm | 0.90" (9/10") | Light autumn jackets, trench coats |
| 40L | 25.40 mm | 1.00" (1") | Winter overcoats, pea coats, heavy wool coats |
| 45L | 28.58 mm | 1.125" (1-1/8") | Oversized statement coat buttons |
Buttonhole Length Sizing Formula
To ensure a button fastens securely without popping open or straining fabric: Buttonhole Length = Button Diameter + Button Thickness + 1.5 mm (1/16 in)
A standard 18L shirt button (11.4 mm diameter, 2.0 mm thickness) requires an exact 15.0 mm buttonhole slit.