Pieds Du Roi to Millimeters (pied to mm)

1 pied du roi equals 324.839385 millimeters (rounded).

1 pied du roi = 324.839385 millimeters

How to convert pieds du roi to millimeters

To convert pieds du roi to millimeters, multiply the number of pieds du roi by 324.839385. The factor is rounded to 10 significant digits. To go the other way, multiply millimeters by 0.003078444444 (rounded).

millimeters = pieds du roi × 324.839385

Example: 10 pieds du roi = 3,248.39385 millimeters.

About these units

Pied Du Roi (pied)

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

The 'king's foot' of the French Ancien Régime, about 32.48 cm; 12 pouces. About 6.6% longer than the English foot.

King's foot is the literal meaning of the name, and the unit was reputed to descend, with little change, from the measures of Charlemagne, which in turn drew on Byzantine and Roman practice. For about a thousand years it stayed close to the same length, though the surviving standards disagree slightly: the foot of the old toise de l'Écritoire is given as 326.6 millimetres, against about 324.8 for the later royal foot.

The figure now used for the pied du roi is 4500/13853 metre, about 32.48 centimetres or 1.066 English feet. This ratio comes from the 1799 law that defined the metre in terms of the Toise of Peru. It was divided into 12 pouces and 144 lignes, while six pieds made one toise.

Wikipedia notes that its own sources vary on details of the standards. The iron toise at the Grand Châtelet was bent before 1668 and replaced by a bar roughly 0.5 percent shorter, which shows how much a nominally fixed unit could drift. Quebec's pied, still seen in land records, is about four parts per million smaller than the French original.

1 pied du roi = 0.324839385 meters (approximately).

Sources: Wikipedia: Pied du roi; Wikipedia: Toise; 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

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