When an unpolarized light of intensity $I_0$ is incident on a polarizing sheet, the intensity of the light which does not get transmitted is:

When unpolarized light of intensity $I_0$ passes through a polarizer, the transmitted intensity is always $I_0/2$, regardless of the orientation of the polarizer.The intensity that is not transmitted is:
$$I_{not\_transmitted}=I_0-\frac{1}{2}{I}_0=\frac{1}{2}{I}_0$$