Square meter

The square meter is the SI-derived unit of area. It has a symbol m² (33A1 in Unicode^[1]). It is defined as the area of a square whose sides measure exactly one meter. The square meter is derived from the SI base unit of the meter, which in turn is defined as the length of the path travelled by light in absolute vacuum during a time interval of ${\displaystyle {\frac {1}{299792458}}}$ of a second.

Adding SI prefixes creates multiples and submultiples. However, as the unit is squared, the order of magnitude difference between units doubles from their comparable linear units. For example, a kilometer is one thousand times the length of a meter, but a square kilometer is one million times the area of a square meter.

A "square meter" is not the same thing as a "meter square" ^[source?] - although it is true that exactly 1 square meter is exactly 1 meter square. But that only works for the number 1; no other.

For example, a square that is 2 meters long and 2 meters wide has 4 square meters of area.

${\displaystyle 2m*2m=4m^{2}}$

But a square that is 4 meters squared would have 4 meters on each side. This means it would have 16 square meters of area.

${\displaystyle 4m*4m=16m^{2}}$

That is, ${\displaystyle (4m)^{2}}$ is 4 meters squared, whereas ${\displaystyle 4m^{2}}$ is 4 square meters.