On-wafer measurements are essential for the characterization of electronic devices at millimeter-wave frequencies. They have been known as challenging and ambitious containing a lot of parasitic effects. While a lot of investigations have been performed for on-wafer measurements of coplanar waveguides (CPW) placed on ceramic chucks, the parasitic effects related to the influence of metal chucks have not been fully investigated yet. This paper demonstrates a systematic study of the metal chuck in conjunction with the parasitic probe effects using two different probe types in mTRL-calibrated CPW measurements through a thorough field analysis.