Button Size Converter
Convert button sizes from ligne to millimeters, inches, and common garment uses. Handy for sewing patterns, vintage button cards, shirts, jackets, coats, and craft projects.
Convert a button size
Enter a ligne size such as 20L, or switch to millimeters or inches to find the closest common button size.
A 20L button is about 12.7 mm across, which is 0.5 inches. It is a common choice for shirts, blouses, and small cardigans.
How button size conversion works
- Use the ligne number from your pattern, vintage button card, or product listing.
- One ligne equals 1/40 inch, so 40L is one inch across.
- Millimeter values are rounded because real buttons can vary slightly by shape, rim, shank, and manufacturer.
- For garment sewing, check the button against the actual buttonhole before buying a full set.
Quick button size chart
| Ligne | Millimeters | Inches | Common use |
|---|
Button size conversion FAQ
What does 20L mean for button size?
20L means 20 ligne. Since each ligne is 1/40 inch, a 20L button is 1/2 inch across, or about 12.7 mm.
Is button ligne the same as millimeters?
No. Ligne is an older button trade size. Millimeters are metric diameter measurements. This converter lets you move between both systems quickly.
What size button is best for shirts?
Many shirt and blouse buttons are around 14L to 20L, depending on the style. Cuff buttons are often smaller than front placket buttons.