Lignes to Millimeters (ligne to mm)

1 ligne equals 2.255829062 millimeters (rounded).

1 ligne = 2.255829062 millimeters

How to convert lignes to millimeters

To convert lignes to millimeters, multiply the number of lignes by 2.255829062. The factor is rounded to 10 significant digits. To go the other way, multiply millimeters by 0.443296.

millimeters = lignes × 2.255829062

Example: 10 lignes = 22.55829062 millimeters.

About these units

Ligne (ligne)

French (Ancien Régime)Historical unit (no longer in standard use)

One twelfth of a pouce (about 2.256 mm). The old French line; watchmakers still quote movement sizes in lignes.

Ligne is simply the French word for line, and the unit sat at the bottom of the Paris measuring ladder: twelve lignes made one pouce, and 144 made one pied du roi. Using the figure adopted in the 1799 metric law, in which one metre equals 443.296 lignes, a ligne comes to about 2.2558 millimetres.

Tailors, cabinetmakers and instrument makers of the Ancien Régime used it for fine dimensions that an inch was too coarse to express. A British line of one twelfth of an English inch also existed until 1824, so the two were similar in spirit but not identical, since the French inch was the longer one.

The unit outlived the monarchy in a few trades. French and Swiss watchmakers still describe the size of a movement or case in lignes, written with a triple prime mark, and milliners measure hat ribbon in it. The button trade uses a different ligne of one fortieth of an inch, about 0.635 millimetres, so the context always has to be checked.

1 ligne = 0.002255829062 meters (approximately).

Sources: Wikipedia: Ligne (unit); Wikipedia: Pied du roi; Wikipedia: Traditional French units of measurement

Millimeter (mm)

Metric (SI)Current unit

One thousandth of a meter. Used in engineering, manufacturing and rainfall measurement.

Carl Friedrich Gauss put the millimeter at the base of his 1832 proposal for absolute units, pairing it with the milligram and the second, although the centimeter-based CGS system later won out among scientists. The name combines the metric prefix milli-, from the Latin for one thousand, with the meter. Since 1983 a millimeter has been tied to the speed of light: it is the distance light covers in 1/299,792,458,000 of a second.

Millimeters are the language of fine mechanical work. Standard rulers are divided into them, digital calipers commonly read to 0.01 mm, and mechanical pencil leads come in 0.5 and 0.7 mm. Copy paper is about 0.1 mm thick, and a thin hair, at 0.02 to 0.04 mm across, is close to the smallest thing the naked eye can see. A wave with a frequency of 300 GHz has a wavelength of 1 mm. An inch is exactly 25.4 mm. One trap for readers in the United States is that mil there traditionally means a thousandth of an inch, not a millimeter.

1 millimeter = 0.001 meters (exactly).

Sources: Wikipedia: Millimetre; Wikipedia: Centimetre-gram-second system of units; NIST Guide to the SI, Appendix B.8: conversion factors

Related conversions

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