A new geometrical model of terry woven fabrics made with cotton yarn has been analyzed to understand the pile yarn path. Theoretical model has been created to predict the porosity of terry woven fabrics depending on their geometrical such as warp and weft spacing pile length pile height pile ratio (terry ratio) type of terry yarn count yarn crimp fabric thickness yarn density and fiber density. Cotton terry woven fabrics were produced with different parameters namely pile height picks per cm and weft yarn count their porosity was determined by measuring fabric density and fiber density and compared with the theoretical porosity. The validity of the theoretical model was confirmed by experimental results. Experiments show that this model gives good results.