To calculate the surface area of a cube, you can use the formula:
\[ \text{Surface Area} = 6s^2 \]
where \( s \) is the length of one edge of the cube.
Given that the length of each edge is 12 inches, we can substitute this value into the formula:
\[ \text{Surface Area} = 6(12^2) = 6(144) = 864 \text{ square inches} \]
Therefore, the surface area of the cube is \( 864 \) square inches.