square metre

SI coherent derived unit

Name	Symbol	Quantity	Base units
square metre	m²	area	m²
The square metre, symbol m², is the SI coherent derived unit of area. One square metre is equal to the area of a square with sides one metre in length.
Definition			c² Δν_Cs^-2
$1 \mspace{4mu} \text{m}^2 \mspace{6mu} = \dfrac{(9 \mspace{4mu} 192 \mspace{4mu} 631 \mspace{4mu} 770)^2}{(299 \mspace{4mu} 792 \mspace{4mu} 458)^2} \mspace{6mu} \dfrac{c^2}{{\Delta \nu _{Cs}}^2}\\ \\ \\ 1 \mspace{4mu} \text{m}^2 \mspace{6mu} \approx 9.402 \mspace{4mu} 391 \mspace{4mu} 313 \mspace{4mu} 904 \mspace{4mu} 046 \mspace{4mu} 861 \times10^{2} \mspace{6mu} c^2 \mspace{4mu} {\Delta \nu _{Cs}}^{-2}$

Area

Area is the quantity that expresses the size of a two-dimensional space.

Orders of magnitude

100 mm²	=	1 cm²	=	0.0001 m²	=	10^-4 m²
100 cm²	=	1 dm²	=	0.01 m²	=	10^-2 m²
100 dm²	=	1 m²	=	1 m²	=	10⁰ m²
100 m²	=	1 dam²	=	100 m²	=	10² m²
100 dam²	=	1 hm²	=	10 000 m²	=	10⁴ m²
100 hm²	=	1 km²	=	1 000 000 m²	=	10⁶ m²

Usage

The name of the unit whose symbol is m² is the square metre. To avoid confusion with shape descriptors such as “metre square”, improvised unit names such as “metre squared” and “metres squared”, should not be used.

The correct use of the unit name, square metre, is particularly important to prevent any misunderstanding. For example, describing an area of 10 m² as “10 metres squared” could be interpreted to mean (10 m)², which would be 100 m².

Similarly, abbreviations, such as “m sq.”, “sq.m.” and “SQ.M.”, must not be used in place of the SI symbol m².

Metre square

A square is a two-dimensional shape with four equal straight sides and four right angles. Squares can be described according to the length of their sides.

e.g. A 1-metre square is a square whose sides are one metre in length, and a 2-metre square is a square whose sides are two metres in length.

A 2-metre square has an area of (2 metres) squared, i.e. 4 square metres.

$(2 \ \text{m})^2 = 2 \ \text{m} \times 2 \ \text{m} = 4 \ \text{m}^2$

Note: A 2-metre square does not have an area of 2 m².

Non-SI units of area

The hectare, symbol ha, is a non-coherent non-SI unit of area, accepted for use with the SI. It is equal to one square hectometre, symbol hm².

Note: SI prefixes must not be used with the hectare.