Seamstresses can purchase rib-knit fabric at fabric stores such as Jo-Ann Fabric and Craft Stores and Hancock Fabrics, as well as online fabric retailers such as Fabric.com. Rib-knit fabrics are often either 100-percent cotton or cotton blends, and are available in a variety of colors.
As of November 2015, Jo-Ann Fabric and Craft Stores offers a cotton-spandex blend rib-knit fabric in seven different colors, including red, navy and ivory. Hancock Fabrics also offers a cotton-spandex blend, while Fabric.com offers a 100-percent cotton lightweight rib knit that is recommended for tank tops and other loungewear. Rib knit is a comfortable, flexible fabric often used for waistbands, cuffs and collars.