Area has the dimension length squared. The SI composite unit of area is the meter squared.

Maple knows the units of area listed in the following table.

An asterisk ( * ) indicates the default context, an at sign (@) indicates an abbreviation, and under the prefixes column, SI indicates that the unit takes all SI prefixes, IEC indicates that the unit takes IEC prefixes, and SI+ and SI- indicate that the unit takes only positive and negative SI prefixes, respectively.  Refer to a unit in the Units package by indexing the name or symbol with the context, for example, are[SI] or b[SI]; or, if the context is indicated as the default, by using only the unit name or symbol, for example, are or b.

The units of area are defined as follows.

An are is defined as $100$ square meters.

The hectare and centare are alternate spellings of the hectoare and centiare, respectively.

A barn is defined as $1.\times {10}^{\mathrm{-28}}$ square meter. This allows physicists the phrase as big as a barn.

A shed is defined as $1.\times {10}^{\mathrm{-52}}$ square meter. The origin of this unit is the same as that of the barn.

A circular mil is defined as the area of a circle with a diameter of $1$ standard mil, that is, $7.853981635\times {10}^{\mathrm{-7}}$ inch squared.

Each of the following units can be based on the standard or US survey mile.

A rood is defined as $\frac{1}{4}$ acre.

An acre is defined as $10$ square Gunter chains.

A lot is defined as $\frac{1}{10}$ square mile.

A section is defined as $1$ square mile.

A township is defined as $36$ square miles.

A planck area is defined as a square planck length.

$\mathrm{convert}\left({'m'}^2\,'\mathrm{dimensions}'\,'\mathrm{base}'=\mathrm{true}\right)$

${\mathrm{length}}^2$

$\mathrm{convert}\left(4.\,'\mathrm{units}'\,{'\mathrm{kilometers}'}^2\,'\mathrm{sections}'\right)$

$1.544408634$

$\mathrm{convert}\left(4.\,'\mathrm{units}'\,{'\mathrm{kilometers}'}^2\,'\mathrm{sections}\left[\mathrm{US\_survey}\right]'\right)$

$1.544402457$

$\mathrm{convert}\left(37\,'\mathrm{units}'\,'\mathrm{barns}'\,{'\mathrm{nanometers}'}^2\right)$

$\frac{37}{10000000000}$