Area
Other units including historical

There are several other common units for area. The are was the original unit of area in the metric system, with:

Though the are has fallen out of use, the hectare is still commonly used to measure land:

Other uncommon metric units of area include the tetrad, the hectad, and the myriad.

The acre is also commonly used to measure land areas, where

An acre is approximately 40% of a hectare.

On the atomic scale, area is measured in units of barns, such that:

The barn is commonly used in describing the cross-sectional area of interaction in nuclear physics.

In South Asia (mainly Indians), although the countries use SI units as official, many South Asians still use traditional units. Each administrative division has its own area unit, some of them have same names, but with different values. There's no official consensus about the traditional units values. Thus, the conversions between the SI units and the traditional units may have different results, depending on what reference that has been used.

Some traditional South Asian units that have fixed value:
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