Ring Sizes Comparison Chart:
U.S British Millimetres Inside Diameter (mm)
3 F 43 13.9
3.5 G 45 14.3
4 H 47 14.7
4.5 I 48 15.1
5 J 49 15.5
5.5 K 50 15.9
6 L 52 16.3
6.5 M 53 16.7
7 N 54 17.1
7.5 O 55 17.5
8 P 57 17.9
8.5 Q 58 18.3
9 R 60 18.7
9.5 S 61 19.1
10 T 62 19.5
10.5 U 63 19.9
11 V 65 20.3
11.5 W 66 20.7
12 X 67 21.1
12.5 Y 68 21.5
13 Z 70 21.9


 

 
Ear Tunnel Comparison Chart:
Gauge Millimetres Inches
18g 1.0mm 5/128”
16g 1.2mm 3/64”
14g 1.6mm 1/16”
12g 2mm 5/64”
10g 2.5mm 3/32”
8g 3mm 1/8”
6g 4mm 5/32”
4g 5mm 3/16”
2g 6mm 1/4”
0g 8mm 1/3”
00g 10mm 3/8”
12mm 1/2”
14mm 9/16”
16mm 5/8”
18mm 11/16”
19mm 3/4”
20mm 3/4”
22mm 7/8”
25mm 1”