A methodology towards de-embedding contact mode scanning microwave microscopy (SMM) reflection measurements is presented. A calibration standard that consists of differently doped stripes is required, while the reflection coefficient amplitude |S11|, is modeled and analyzed in the linear scale, instead of the commonly adopted dB scale. This allows the straightforward experimental determination of important parameters such as the effective tip radius and the magnitude of stray capacitances. Values of 145 nm and 22 fF have been obtained respectively. The proposed methodology can be easily and repeatedly performed during the experimental procedure, offering in this way the necessary de-embedding to get an enhanced accuracy on SMM measurements for semiconductors characterization.