We have done many counts, strength and twist tests - which are considered the most important physical properties that determine yarns quality specification - on cotton yarns at the industrial researches& tests center. The researcher has depended on this tests results to find out formulas which match between physical properties of yarns, starting from common formulas then he has proved them by analysis of results that we got from graphic tests instruments, then we have figured out proportion constants between these physical properties from curves that we have got by tests results exemplification and we have shown if these constants describe common constants or new constants.