Frustum Culling

How do I calculate if an object is outside of the camera’s viewing area?

I tried getting the modelview matrix and multiplying it by
my x y and z coordinate of my object.
Then I multiplied my answer by the projection matrix.

I know the zfar znear and Frustum Height and Width value.

Do I say
if z > zfar then cull
if z < near then cull
if x > fW then cull
if x < -fW then cull
if y > fH then cull
if y < -fH then cull

Try this thread: