Scaling relationships among the relevant reactor, driver, and target parameters and gain for three heavy-ion target concepts are presented. These relations include scaling laws for the required peak power and ion energy, the fuel fractional burnup, and the fraction of energy released in charged particles and X rays as a function of the target radius, the hydrodynamic coupling efficiency, and the incident ion energy. The impact of polarized deuterium-tritium fuel on the scaling relations is also shown, and the direct-drive concept is examined to illustrate some of the ideas used in developing a hydrodynamic efficiency model.