Copyright © 2016 SPIE. In this paper, we report a computational and experimental study using tunable infrared (IR) metamaterial absorbers (MMAs) to demonstrate frequency tunable (7%) and amplitude modulation (61%) designs. The dynamic tuning of each structure was achieved through the addition of an active material - liquid crystals (LC) or vanadium dioxide (VO2) - within the unit cell of the MMA architecture. In both systems, an applied stimulus (electric field or temperature) induced a dielectric change in the active material and subsequent variation in the absorption and reflection properties of the MMA in the mid- to long-wavelength region of the IR (MWIR and LWIR, respectively). These changes were observed to be reversible for both systems and dynamic in the LC-based structure.