The development of elastomeric face seals is imperative for NASA’s manned space flight program. Lacking in the development of state-of-the-art space seals was a technique for predicting the performance of candidate designs prior to experimental characterization. To this end, a physics-based model for compressible permeation in elastomeric face seals was developed to provide a predictive methodology for designers and researchers. In this novel approach for seal research, compressibility effects and the dependence of permeability on pressure was retained. Two independent permeation parameters arose from an exact, analytical solution to the one-dimensional permeation transport equations. The application of the derived transport equations and the developed permeability coefficients resulted in a noteworthy and practical tool for seal researchers to predict the leak rate of alternative geometries. For an example in the methodology, the characterization of a candidate space seal material, silicone elastomer S0383-70, was performed. Results illustrated the model’s capability for capturing the permeation leak rate of elastomeric seals for various pressure differentials.