Sizing Chart for Rings

To measure the inside diameter, measure the inside of a ring that fits from left to right with a ruler.

Australian Size  US Size

Inside Diameter

(mm)

Inside Circumference

(mm)
J 4 3/4 15.5 48.7
J 1/2 5 15.7 49.3
K 5 1/4 15.9 49.9
K 1/2 5 1/2 16.1 50.6
L 5 3/4 16.3 51.2
L 1/2 6 16.5 51.8
M 6 1/4 16.7 52.5
M 1/2 6 1/2 16.9 53.1
N 6 3/4 17.1 53.8
N 1/2 7 17.3 54.4
O 7 1/4 17.5 55.0
O 1/2 7 1/2 17.7 55.7
P 7 3/4 17.9 56.3
P 1/2 8 18.1 56.9
Q 8 1/4 18.3 57.6
Q 1/2 8 1/2 18.5 58.2
R 8 3/4 18.7 58.9
R 1/2 9 18.9 59.5
S 9 1/4 19.2 60.1
S 1/2 9 1/2 19.4 60.8
T 9 3/4 19.6 61.4
T 1/2 10 19.8 62.1
U 10 1/4 20.0 62.7
U 1/2 10 1/2 20.2 63.3
V 10 3/4 20.4 64.0
V 1/2 11 20.6 64.6
W 11 1/4 20.8 65.2
W 1/2 11 1/2 21.0 65.9
X 11 3/4 21.2 66.5
W 1/2 12 21.4 67.2
Y 12 1/4 21.6 67.8
Z 12 1/2 21.8 68.4