Acre

An acre is 4047 square metres

How much is an acre?

1 Acre (International):

$\small{ \begin{array}{|rcll|} \hline 1\ \text{Acre (International)} &=& 4\ \text{roods} \cdot \dfrac{ 40\ \text{perches}} { 1\ \text{rood} } \cdot \dfrac{ 30\frac14\ \text{sq. yds} } { 1\ \text{perch} } \cdot \dfrac{ 9\ \text{sq. ft} } { 1\ \text{sq. yds} } \cdot \dfrac { 12^2\ \text{sq. in} } { 1\ \text{sq. ft} } \cdot \dfrac { 0.0254^2\ m^2 } { 1\ \text{sq. in} }\\\\ &=& 4 \cdot 40 \cdot 30\frac14 \cdot 9 \cdot 12^2 \cdot 0.0254^2\ m^2 \\\\ &=& 4 \cdot 40 \cdot 30.25 \cdot 9 \cdot 12^2 \cdot 0.0254^2\ m^2 \\\\ \mathbf{1\ \text{Acre (International)}} &\mathbf{=}& \mathbf{4046.85642240\ m^2 } \\ \hline \end{array} }$

1 Acre (U.S. Survey):

$\small{ \begin{array}{|rcll|} \hline 1\ \text{Acre (U.S. Survey)} &=& 4\ \text{roods} \cdot \dfrac{ 40\ \text{perches}} { 1\ \text{rood} } \cdot \dfrac{ 30\frac14\ \text{sq. yds} } { 1\ \text{perch} } \cdot \dfrac{ 9\ \text{sq. ft} } { 1\ \text{sq. yds} } \cdot \dfrac { \left( \frac{1200}{3937} \right)^2\ \ m^2 } { 1\ \text{sq. Survey ft} } \cdot \\\\ &=& 4 \cdot 40 \cdot 30\frac14 \cdot 9 \cdot \left( \frac{1200}{3937} \right)^2\ m^2 \\\\ &=& 4 \cdot 40 \cdot 30.25 \cdot 9 \cdot \left( \frac{1200}{3937} \right)^2\ m^2 \\\\ \mathbf{1\ \text{Acre (U.S. Survey)}} &\mathbf{=}& \mathbf{4046.87260987\ m^2 } \\ \hline \end{array} }$