Octi Ring Size Chart
| INSIDE DIAMETER (MM) | US | UK |
| 14 | 3 | F |
| 14.5 | 3.5 | G |
| 15 | 4 | H |
| 15.3 | 4.5 | I |
| 15.6 | 5 | J |
| 16.2 | 5.5 | K |
| 16.6 | 6 | L |
| 16.9 | 6.5 | M |
| 17.2 | 7 | N |
| 17.8 | 7.5 | O |
| 18.1 | 8 | P |
| 18.5 | 8.5 | Q |
| 19.1 | 9 | R |
| 19.4 | 9.5 | S |
| 19.7 | 10 | T |
| 20.4 | 10.5 | U |
| 20.7 | 11 | V |
| 21 | 11.5 | W |
| 21.6 | 12 | X |
| 22 | 12.5 | Y |
| 22.3 | 13 | Z |