This article presents a numerical analysis of mixing and pressure drop in a spiral micromixer with four different inlet flow path configurations. Micromixers Type 1 and Type 2 (M-Type 1 and M-Type 2) have Y-shaped and T-shaped entry into the main channel with fluid entry into a spiral channel at 90°, whereas, inMicromixers Type 3 and Type 4 (M-Type 3 and M-Type 4), the entries of fluid are in line with spiral channel. The mass fraction contours of the species, velocity vectors, mixing efficiency, and pressure drops are analyzed for Reynolds number in the range 1 ≤ Re ≤ 100. The results show that the mixing efficiency first decreases with the increase in Re and then increases with Re values. In contrast, pressure drops and mixing performance increase with the increase in Re values irrespective of the micromixer design. Higher mixing is observed inmicromixers having Y-shaped inlets. The mixing efficiency of 97.2% is observed in M-Type 3, followed by 94% in M-Type 1. In M-Type 2 and M-Type 4, the values of mixing efficiency are 89% and 90.3%, respectively. The mixing performance of micromixers in M-Type 1 and M-Type 3 is lower than M-Type 2 and M-Type 4.