To find the height of the cylinder, we can use the formula for the volume of a cylinder:
\[ V = \pi r^2 h \]
where \( V \) is the volume, \( r \) is the radius, and \( h \) is the height.
From the problem, we know:
- The radius \( r = 7 \) mm
- The volume \( V = 441\pi \) mm\(^3\)
We can substitute these values into the volume formula:
\[ 441\pi = \pi (7^2) h \]
First, calculate \( 7^2 \):
\[ 7^2 = 49 \]
Now, substitute that into the equation:
\[ 441\pi = \pi (49) h \]
Next, we can divide both sides of the equation by \( \pi \) (assuming \( \pi \neq 0 \)) to simplify:
\[ 441 = 49h \]
Now, solve for \( h \) by dividing both sides by 49:
\[ h = \frac{441}{49} \]
Calculating that gives:
\[ h = 9 \]
Thus, the height of the cylinder is
\[ \boxed{9} \text{ mm}. \]