We present Error Compensation Software (ECS) which uses a decic polynomial model and three-dimensional surface measurement data for the fabrication of high precision freeform mirrors. ECS is designed based on a graphic user interface that includes an error calculation mechanism and surface distribution maps, and it accepts the Ultrahigh Accurate 3D Profilometer (UA3P) measurement data of the fabricated mirror surface. It exports surface coefficients and tool paths for the Single Point Diamond Turning (SPDT) machine which allows engineers to utilize the software during the compensation process. The ECS is based on Visual C++ and runs on the Windows operating system. The error compensation process with ECS has been applied to the 90 mm diameter aluminum freeform mirrors for usage in view infrared satellites, and the root mean square and peak-to-valley surface errors were reduced from 1.52 to 0.11 μm, and from 7.05 to 1.99 μm, respectively, satisfying the requirement of the infrared camera.