Three-dimensional reciprocal space mapping (3D-RSM) offers crucial insights into the intricate microstructural properties of materials, including spatial domain distribution, directional long-range ordering, multilayer-substrate mismatch, layer tilting, and defect structure. Traditionally, 3D-RSMs are conducted at synchrotron facilities where instrumental resolution is constrained in all three directions. Lab-based sources have often been considered suboptimal for 3D-RSM measurements due to poor instrumental resolution along the axial direction. However, we demonstrate that, by employing three-dimensional reciprocal space x-ray computed tomography (RS-XCT), the same perceived limitation in resolution can be effectively leveraged to acquire high quality 3D-RSMs. Through a combination of ultrafast reciprocal space mapping and computed tomography reconstruction routines, lab-based 3D-RSMs achieve resolutions comparable to those obtained with synchrotron-based techniques. RS-XCT introduces a practical modality for lab-based x-ray diffractometers, enabling high-resolution 3D-RSM measurements on a variety of materials exhibiting complex three-dimensional scattering landscapes in reciprocal space.