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are

unit of area measurement
Also known as: a
Written and fact-checked by
Britannica Editors
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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History

are, unit of area in the metric system, equal to 100 square metres and the equivalent of 0.0247 acre. Its multiple, the hectare (equal to 100 ares), is the principal unit of land measurement for most of the world. The are was the basic unit of area when the metric system was first decreed in France in 1795. When the International System of Units (SI) was adopted in 1960, the square metre replaced the are as the unit of area, but the International Bureau of Weights and Measures has accepted the hectare as a commonly used unit that can be used with the SI.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Erik Gregersen.