With improved technology, small satellites have opened space to customers such as universities conducting research, companies testing products, and countries unable to support a traditional large space program. As more small satellites operate in space, a theoretical concept of their capabilities is useful not only for satellite designers, but also current spacecraft operators and space situational awareness observers. This study examines the maximum communication capability of a S-band geostationary small satellite as part of a larger Small Satellite Capability Analysis study. Power production using body-mounted solar cells is maximized for cubic satellites with characteristic lengths from ten centimeters to one meter. The maximum data rate is calculated using link analysis and QPSK coding procedures. Multiple ground station sizes and allocated volumes for the transmitter are examined, and ideal conditions are used throughout the study. While the maximum data rate increases with satellite size and ground station antenna size, this procedure gives a “physics-only” solution that is far beyond the capabilities of current satellite components. Technological limits are applied to the solution to find the realistic maximum communication capability. A few general trends are apparent in the results. The input power required by the transmitter determines the minimum size satellite that can support a given transmitter. If only a small portion of the satellite volume is allocated for the transmitter, the transmitter volume also dictates the minimum size satellite that can support a given transmitter. The supported transmitter determines the output power and maximum bandwidth, which determine the resulting data rate. These limitations are the areas of technological development necessary to expand the future communication capability of small satellites. A trendline of allocated payload volumes based on satellite size is also developed to indicate the capability of the analyzed small satellite to accomplish other tasks. This is combined with the communication performance of satellites (with small transmitter-allocated internal volumes) to create a 3-D solution space for the overall capability of small satellites