A good understanding of woven fiber preform permeabilities is critical in the design and optimization of the composite molding processes, yet these issues remain unresolved in the literature. Many have attempted to address permeability predictions for flat undeformed fiber preform, but few have investigated permeability variations for complex three-dimensional molds. In this study, the objectives are to: (i) first provide a brief review of existing methods for the prediction of the fiber mat permeability; (ii) postulate a more realistic representation of a unit cell to account for such fabric structures as crimp, tow spacing and the like; and (iii) apply computational approximations for predicting effective permeabilities for use in the modeling of structural composites processes. The Stokes equation is used to model the flow in the inter-tow region of the unit cell, and in the intra-tow region, the Brinkman's equation is used. Preliminary permeability prediction calculations are performed for a three-dimensional unit cell model representative of PET 61 woven fabric. The results showed good agreement with experimental data published in literature.