Size of buttons is often labelled in so called English Ligne (L or '). One English Ligne is 1/40 of English inch. Exactly 0,635 mm.
| Eng. ligne | mm |
| 6" | 3,81 |
| 8" | 5,08 |
| 10" | 6,35 |
| 12" | 7,62 |
| 14" | 8,89 |
| 16" | 10,16 |
| 18" | 11,43 |
| 20" | 12,7 |
| 22" | 13,97 |
| 24" | 15,24 |
| 26" | 16,51 |
| 28" | 17,78 |
| 30" | 19,05 |
| 32" | 20,32 |
| 34" | 21,59 |
| 36" | 22,86 |
| 38" | 24,13 |
| 40" | 25,4 |
| 42" | 26,67 |
| 44" | 27,94 |
| 46" | 29,21 |
| 48" | 30,48 |
| 50" | 31,75 |
| 52" | 33,02 |
| 54" | 34,29 |
| 56" | 35,56 |
| 58" | 36,83 |
| 60" | 38,1 |
