How do I know what size lace to purchase?

Sizing Chart. Number of Eyelets    Lace Length. 3 Eyelets                   30 Inches. 4 Eyelets                   36 Inches. 5-6 Eyelets                45 Inches. 6-7 Eyelets               54 Inches. 7-8 Eyelets      63 Inches. 8-9 Eyelets