An investigation of several fundamental limits of machine design indicate that a machine fitting the specifications of the Tokamak Fusion Core Experiment (TFCX) can be built with both a superconducting toroidal field (TF) coil set and a plasma major radius of less than 3.2 m. This small size is achieved by accepting a peak nuclear heat load of 50 kW·m−3 in the TF coil inner leg while operating at a 10-T maximum field with a current density of 35 A·mm−2 in the winding pack. This performance, high by traditional standards, is justified based on developments in forced flow conductor technology using Nb3Sn composite superconductors.