As a guideline, if you are buying shoelaces, it is recommended that for
- 3-4 eyelets, get 24/27 inches 61/69 cm
- 4-5 eyelets, get 30/36 76/91
- 5-6 eyelets, get 40/45 102/114
Good advice, but hard to remember.
Instead, multiple the number of eyelets by 8.5 and you will get the right size.