The study is to find out changes in weight of cotton knit fabrics in pretreatments of dyeing. Single jersey, single lacoste, 1x1 rib, 1x1 lycra rib, 2x2 rib & terry fabrics were used for this research and processed them in different pretreatments of dyeing. Standard recipes were followed with right chemicals were used in every stage. All the processes were conducted in a reputed industry and modern machines were used at every process. After values of weight changes at each stage were carefully measured maintaining same atmospheric condition. It was found that weight changing rate is different for the different knit structured fabric though same recipes and procedures were followed for all of the fabric samples in a particular stage. Finally, the reasons of variation in weight change were explained logically.