Previous Term Next Term Rows Per Inch (RPI) Rows per inch (RPI) refers to the number of yarns in one inch that run along the length of a woven carpet. In tufted carpet, this is referred to as stitches per inch (SPI). Sources The Carpet and Rug Institute (CRI) Related Terms Fumed Wood Shirred Drapery Header Accordion Pleat Pencil Pleat Photochromic Flat Pleat Was this insightful? Yes No