The required length varies based on shoe size and width as well as the placement and type of eyelets. When a range of length is listed, the shorter length is generally for women's and children's shoes and the longer length is for men's shoes. The reference chart is offered as a guide. Pairs of eyelets/Lace length: 2-3 prs/27 inch; 4 prs/30-36 inch; 5 prs/40-45 inch; 6-7 prs/45-54 inch; 8-9 prs/54-63 inch; 10-11 prs/63-72 inch.