An understanding of the power that can be harvested from pyroelectric materials and its dependence on material properties, geometry and boundary condition is crucial to the design of energy harvesting devices using these materials. In this paper, simple analytical expressions are developed for ideal voltage, power and power densities as a function of pyroelectric constant, permittivity, surface area, thickness, temperature variation and rate of change for unclamped samples. Experiments are performed to specifically study the effect of geometry and are compared with theoretical predictions.