Physical properties of fabric basically depend on fabric cover and porosity. Other fabric parameters that influence the air transmittance of a fabric are type of stitches used, type of yarn, linear density, twist factor in the yarn, stitch density, thickness, tightness factor and fractional cover of fabric and moisture content which has a circuitous effect on those parameters. Many researchers had already derived so many relationships among those parameters and the fabrics properties. But, air transmittance rate may influence other comfort properties of the fabric. Our investigation shows the relationship of different parameters which can alter the transmittance of air through the plain knitted fabric. Here, a little change in the structure can alter the air transmittance which has been represented graphically.