Please note ring sizes can vary slightly within each size.
All measurements are from the inner diameter of the ring.

Measurement
Inside Diameter
Measurement
Inside Diameter
SIZE
Inches
Millimeters
#6
0.65
16.5
#7
0.68
17.3
#8
0.71
18.1
#9
0.74
18.9
#10
0.78
19.8
#11
0.81
20.6
#12
0.84
21.4
#13
0.87
22.2