US Master Chart
Master US Ring Size Chart
Every standard US numerical size mapped exactly to inside diameter and inside circumference in millimeters.
US Sizes to Millimeters
| US Size | Inside Circumference (mm) | Inside Diameter (mm) |
|---|---|---|
| 3 | 44.2 | 14.1 |
| 3.5 | 45.5 | 14.5 |
| 4 | 46.8 | 14.9 |
| 4.5 | 48.0 | 15.3 |
| 5 | 49.3 | 15.7 |
| 5.5 | 50.6 | 16.1 |
| 6 | 51.9 | 16.5 |
| 6.5 | 53.1 | 16.9 |
| 7 | 54.4 | 17.3 |
| 7.5 | 55.7 | 17.7 |
| 8 | 57.0 | 18.1 |
| 8.5 | 58.3 | 18.5 |
| 9 | 59.5 | 18.9 |
| 9.5 | 60.8 | 19.4 |
| 10 | 62.1 | 19.8 |
| 11 | 64.6 | 20.6 |
| 12 | 67.2 | 21.4 |
| 13 | 69.7 | 22.2 |
Written by Evelyn Moore
Evelyn is a certified GIA Gemologist with over a decade of experience in fine jewelry sizing and design. She ensures all conversion charts and measuring advice strictly adhere to ISO 8653 standards.