A circular disk mold is sometimes employed to test how a reinforced polymer will induce part warpage or distortion after removal from an injection mold. These polymer disks are modeled by developing an analogy to axially symmetric disks that have the reinforcement either in the disk radial or tangential direction and warp to a cup or saddle shaped disk during cooling. The governing mechanisms causing warpage are discussed with analytical and numerical models employed to quantify the impact of in-plane thermal anisotropy on warpage. The cup and saddle warpage formulae that are derived can guide the engineer on estimating the underlying polymer properties as well. as evaluating the impact of part design on thermal warpage.