Pieds Du Roi to Inches (pied to in)

1 pied du roi equals 12.78895216 inches (rounded).

1 pied du roi = 12.78895216 inches

How to convert pieds du roi to inches

To convert pieds du roi to inches, multiply the number of pieds du roi by 12.78895216. The factor is rounded to 10 significant digits. To go the other way, multiply inches by 0.07819248889 (rounded).

inches = pieds du roi × 12.78895216

Example: 10 pieds du roi = 127.8895216 inches.

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

Inch (in)

US & ImperialCurrent unit

1/12 of a foot. Defined as exactly 25.4 millimeters since 1959, when the US and Commonwealth countries agreed a common international inch.

Latin uncia, meaning one-twelfth, is the root of both inch and ounce, and it passed into Old English as ynce. Roman measurers divided their foot into twelve unciae, and the English inch kept that twelfth. After 1066 an inch was reckoned as three barleycorns, and a 1324 statute attributed to Edward II spelled out the definition as three grains of barley, dry and round, placed end to end lengthwise. For centuries the inch was simply a twelfth of a foot, or a thirty-sixth of a yard, and the US and UK each kept their own copy of the standard yard.

Those copies differed slightly until the 1959 international agreement fixed the yard at exactly 0.9144 meter, which made the inch exactly 25.4 millimeters. The US adopted it in 1959 and the UK ratified it in 1963, effective 1964. Today the inch is still the customary unit in the United States and Canada, and the UK keeps it on road signs. Worldwide it also names display diagonals, wheel rims, tire codes and pipe sizes.

1 inch = 0.0254 meters (exactly).

Sources: Wikipedia: Inch; Wikipedia: Yard; NIST Guide to the SI, Appendix B.8: conversion factors

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