Toise

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

Six pieds du roi, about 1.949 m. Used to define the length of the meter: the first metric standard was based on a ratio to the toise.

1 toise = 1.94903631 meters (approximately).

About the toise

Latin tensa brachia, meaning outstretched arms, is the root of toise, and the unit began as a fathom-like span of a man's reach. Under the Ancien Régime it was fixed at six pieds du roi, 72 pouces or 864 lignes, which equals about 1.949 metres by the 1799 definition.

Its physical standard was an iron bar set into a wall of the Grand Châtelet in Paris, in place before 1394. After the bar bent, a replacement made in 1667 was about half a percent shorter. In 1735 two new geodetic standards were calibrated against it, and one of them, the Toise of Peru, took part in the Spanish-French Geodesic Mission and became the official standard in 1766.

The toise also shaped the metre. The 1799 metre was defined as 443.296 lignes, or 3 pieds and 11.296 lignes of the Toise of Peru, which matches 13,853 parts of 27,000 of a toise. Later French usage varied: from 1812 to 1840 the customary toise was set to exactly 2 metres, and other countries had their own toises, such as about 1.8 metres in Switzerland.

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

Toise conversion chart

1 toise expressed in every other length unit:

More French (Ancien Régime) units

• ligne (length)
• pouce (length)
• pied du roi (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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