To find the area of a circle, you can use the formula:
\[ A = \pi r^2 \]
where \( r \) is the radius of the circle. The radius is half of the diameter. Given that the diameter is 12 inches, we can calculate the radius:
\[ r = \frac{12}{2} = 6 \text{ in.} \]
Now, we can substitute the radius into the area formula:
\[ A = \pi (6)^2 = \pi \times 36 = 36\pi \]
Thus, the area of the circle in terms of \(\pi\) is
\[ \boxed{36\pi} \text{ square inches.} \]