Ring Sizes
| United States size | Avg. diameter in inches | Length in inches | British equivalent | French equivalent | German equivalent | Japanese equivalent | Swiss equivalent | 
| 000 | .390 | --- | --- | --- | --- | --- | --- | 
| 00 | .422 | --- | --- | --- | --- | --- | --- | 
| 0 | .454 | 1.429 | --- | --- | --- | --- | --- | 
| 1/2 | --- | --- | A | --- | --- | --- | --- | 
| 3/4 | --- | --- | A-1/2 | --- | --- | --- | --- | 
| 1 | .487 | 1.528 | B | --- | --- | 1 | --- | 
| 1-1/4 | --- | --- | B-1/2 | --- | --- | --- | --- | 
| 1-1/2 | .503 | --- | C | --- | --- | --- | --- | 
| 1-3/4 | --- | --- | C-1/2 | --- | --- | --- | --- | 
| 2 | .520 | 1.632 | D | 41-1/2 | 13-1/2 | 2 | 1-1/2 | 
| 2-1/4 | --- | --- | D-1/2 | --- | --- | --- | --- | 
| 2-1/2 | .536 | --- | E | 42-3/4 | 13-3/4 | 3 | 2-3/4 | 
| 2-3/4 | --- | --- | E-1/2 | --- | --- | --- | --- | 
| 3 | .553 | 1.735 | F | 44 | 14 | 4 | 4 | 
| 3-1/8 | --- | --- | F-1/2 | --- | --- | --- | --- | 
| 3-3/8 | --- | --- | G | 45-1/4 | --- | 5 | 5-1/4 | 
| 3-1/2 | .569 | --- |  | --- | 14-1/2 | --- | --- | 
| 3-5/8 | --- | --- | G-1/2 | --- | --- | 6 | --- | 
| 3-3/4 | --- | --- | H | 46-1/2 | --- | --- | 6-1/2 | 
| 4 | .585 | 1.835 | H-1/2 | --- | 15 | 7 | --- | 
| 4-1/4 | --- | --- | I | 47-3/4 | --- | --- | 7-3/4 | 
| 4-1/2 | .601 | --- | I-1/2 | --- | 15-1/4 | 8 | --- | 
| 4-5/8 | --- | --- | J | 49 | --- | --- | 9 | 
| 5 | .618 | 1.943 | J-1/2 | --- | 15-3/4 | 9 | --- | 
 
| United States size | Avg. diameter in inches | Length in inches | British equivalent | French equivalent | German equivalent | Japanese equivalent | Swiss equivalent | 
| 5-1/8 | --- | --- | K | 50 | --- | --- | 10 | 
| 5-3/8 | --- | --- | K-1/2 | --- | --- | 10 | --- | 
| 5-1/2 | .634 | --- | L | 51-3/4 | 16 | --- | 11-3/4 | 
| 5-7/8 | --- | --- | L-1/2 | --- | --- | --- | --- | 
| 6 | .650 | 2.045 | M | 52-3/4 | 16-1/2 | 12 | 12-3/4 | 
| 6-1/4 | --- | --- | M-1/2 | --- | --- | --- | --- | 
| 6-1/2 | .666 | --- | N | 54 | --- | 13 | 14 | 
| 6-3/4 | --- | --- | N-1/2 | --- | 17 | --- | --- | 
| 7 | .683 | 2.15 | O | 55-1/4 | 17-1/4 | 14 | 15-1/4 | 
| 7-1/4 | --- | --- | O-1/2 | --- | --- | --- | --- | 
| 7-1/2 | .699 | --- | P | 56-1/2 | --- | 15 | 16-1/2 | 
| 7-3/4 | --- | --- | P-1/2 | --- | --- | --- | --- | 
| 8 | .716 | 2.25 | Q | 57-3/4 | 18 | 16 | 17-3/4 | 
| 8-1/4 | --- | --- | Q-1/2 | --- | --- | --- | --- | 
| 8-1/2 | .732 | --- | --- | --- | --- | 17 | --- | 
| 8-5/8 | --- | --- | R | 59 | --- | --- | 19 | 
| 8-7/8 | --- | --- | R-1/2 | --- | --- | --- | --- | 
| 9 | .748 | 2.35 | --- | --- | 19 | 18 | --- | 
| 9-1/8 | --- | --- | S | 60-1/4 | --- | --- | 20-1/4 | 
| 9-3/8 | --- | --- | S-1/2 | --- | --- | --- | --- | 
| 9-1/2 | .764 | --- | --- | --- | 19-1/2 | 19 | --- | 
| 9-5/8 | --- | --- | T | 61-1/2 | --- | --- | 21-1/2 | 
| 10 | .781 | 2.46 | T-1/2 | --- | 20 | 20 | --- | 
| 10-1/4 | --- | --- | U | 62-3/4 | --- | 21 | 22-3/4 | 
| 10-1/2 | .797 | --- | U-1/2 | --- | 20-1/4 | 22 | --- | 
 
| United States size | Avg. diameter in inches | Length in inches | British equivalent | French equivalent | German equivalent | Japanese equivalent | Swiss equivalent | 
| 10-5/8 | --- | --- | V | 63 | --- | --- | 23-3/4 | 
| 11 | .814 | 2.56 | V-1/2 | --- | 20-3/4 | 23 | --- | 
| 11-1/8 | --- | --- | W | 65 | --- | --- | 25 | 
| 11-3/8 | --- | --- | W-1/2 | --- | --- | --- | --- | 
| 11-1/2 | .830 | --- | --- | --- | 21 | 24 | --- | 
| 11-5/8 | --- | --- | X | 66-1/4 | --- | --- | 26-1/4 | 
| 11-7/8 | --- | --- | X-1/2 | --- | --- | --- | --- | 
| 12 | .846 | 2.63 | Y | 67-1/2 | 21-1/4 | 25 | 27-1/2 | 
| 12-1/4 | --- | --- | Y-1/2 | --- | --- | --- | --- | 
| 12-1/2 | .862 | --- | Z | 68-3/4 | 21-3/4 | 26 | 28-3/4 | 
| 12-5/8 | --- | --- | Z-1/2 | --- | --- | --- | --- | 
| 13 | .879 | 2.76 | --- | --- | 22 | 27 | --- |