Silicon carbide (SiC) is an interesting semiconductor for MEMS devices. The high-value Young’s modulus of silicon carbide facilitates high frequencies and quality (Q) factors in resonant devices built with double-clamped beams. The aim of this work is to achieve the determination and modeling of the Q-Factor for samples of micromachined 3C-SiC film on silicon substrates. This study demonstrates that the experimental datasets created by Romero, integrated with the thicker samples reported in this work, fit the theoretical model presented in the paper. Furthermore, the influence of the crystallographic defects present at the 3C-SiC/Si interface on the Q-factor can be observed both in the analytical model of Romero and in the numerical model present in COMSOL. 3C-SiC layers with thickness greater than 600 nm are needed to achieve an ideal performance from double-clamped beams.