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.

1 pied du roi = 0.324839385 meters (approximately).

About the pied du roi

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.

Sources: Wikipedia: Pied du roi; Wikipedia: Toise; Wikipedia: Traditional French units of measurement

Pied Du Roi conversion chart

1 pied du roi expressed in every other length unit:

More French (Ancien Régime) units

• ligne (length)
• pouce (length)
• toise (length)
• lieue (Paris league) (length)
• arpent (North American) (area)
• degree Réaumur (temperature)
• degree Delisle (temperature)
• poncelet (power)
• pièze (pressure)
• sthène (force)

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