# Ligne

Ligne
Unit systemFrench
Unit oflength
Conversions
1 ligne in ...... is equal to ...
French units   12 Truchet point
1/12 pouce
metric (SI) units   2.2558 mm
imperial/US units   0.08881 in

The ligne (pronounced [liɲ] ) or line or Paris line,[1] is a historic unit of length used in France and elsewhere prior to the adoption of the metric system in the late 18th century, and used in various sciences after that time.[2][3] The loi du 19 frimaire an VIII (Law of 10 December 1799) states that one metre is equal to exactly 443.296 French lines.[4]

It is vestigially retained today by French and Swiss watchmakers to measure the size of watch movements,[5] in button making, and ribbon manufacture.

## Current use

### Watchmaking

The ligne is still used by French and Swiss watchmakers

There are 12 lignes to one French inch (pouce). The standardized conversion for a ligne is 2.2558291 mm (1 mm = 0.443296 ligne), and it is abbreviated with the letter L or represented by the triple prime, ‴. One ligne is the equivalent of 0.0888 international inch.

This is comparable in size to the British measurement called "line" (one-twelfth of an English inch), used prior to 1824.[6]

### Buttonmaking

In the 18th century German button makers began to use the term ligne to measure the diameter of buttons. The consensus definition was that a ligne was the measurement of a round wick, folded flat. In this sense it measures ​140 of an inch, but not exactly, for there were several inches in the kingdoms and petty states of Germany at that time.

Such a measurement became the American measurement called "line", being one-fortieth of the US-customary inch, used measure buttons, probably introduced by German immigrants.[7][better source needed] It remains in US use today for buttons and snaps.[citation needed]

### Hatmaking

Ligne is used in measuring the width of ribbons in men's hat bands,[8] at 11.26 per inch.[9]