Mask-wearing emerged as the key safety measure to prevent the spreading of COVID-19. In this study, we hypothesized a model to quantify the leakage flow rate through the face mask based on a parallel resistance model. The tests were performed in two ways: (I) mask material test, in which all masks were sealed to a flange to measure transmission through a full mask and prevent leakage around the edges, and (II) mannequin mask test, in which masks were fitted to a mannequin head tightly. For all masks, the pressure drop was measured at eight different flow rates between 5 and 85 LPM, and it was increased linearly with the flow rate (r2 > 0.98). The results of the study showed that the leakage flow rate was 10% of the total flow rate, even for the best-fitted N95 filtering facepiece respirators (FFRs) and KN95 masks. They showed higher resistance to the leaks. The procedure masks and cloth masks showed a leakage flow rate of 25% of the value of the total flow rate, quite a large proportion of the flow. They had lower resistance to leaks.