A generic reactor model is used to examine the economic viability of electricity generation by magnetic fusion. The simple model uses components that are representative of those used in previous reactor studies of deuterium-tritium burning tokamaks, stellarators, bumpy tori, reversed-field pinches, and tandem mirrors. Conservative costing assumptions are made. The generic reactor is not a tokamak but rather it is intended to emphasize what is common to all magnetic fusion reactors. The reactor uses a superconducting toroidal coil set to produce the dominant magnetic field. To this extent, it is not as good an approximation to systems, such as the rev er sed-field pinch, in which the main field is produced by a plasma current. The main output of the study is the cost of electricity as a function of the weight and size of the fusion core — blanket, shield, structure, and coils. The model shows that a 1200-MW(electric) power plant with a fusion core weight of ∼10000 tonnes should be competitive in the future with fission and fossil plants. Sensitivity studies that vary the assumptions show that this result is not sensitively dependent on any given assumption. Of particular importance is the result that this scale of fusion reactor may be realized with only moderate advances in physics and technology capabilities.