Ring Size Conversion Chart

Ring Size Diameter (Inside) Circumference (Inside)
UK / Australia USA / Canada MM Inches MM Inches
A 1/2 11.95 0.47 37.54 1.49
A 1/2 3/4 12.18 0.48 38.26 1.51
B 1 12.37 0.49 38.86 1.53
B 1/2 1 1/4 12.6 0.50 39.58 1.56
C 1 1/2 12.78 0.50 40.15 1.58
C 1/2 1 3/4 13 0.51 40.84 1.61
D 2 13.21 0.52 41.5 1.63
D 1/2 2 1/4 13.41 0.53 42.13 1.66
E 2 1/2 13.61 0.54 42.76 1.68
E 1/2 2 3/4 13.83 0.54 43.45 1.71
F 3 14.05 0.55 44.14 1.74
F 1/2 3 1/8 14.15 0.56 44.45 1.75
F 3/4 3 1/4 14.25 0.56 44.77 1.76
G 3 3/8 14.36 0.57 45.11 1.77
G 1/4 3 1/2 14.45 0.57 45.4 1.79
G 1/2 3 5/8 14.56 0.57 45.74 1.8
H 3 3/4 14.65 0.58 46.02 1.81
H 1/2 4 14.86 0.59 46.68 1.84
I 4 1/4 15.04 0.59 47.25 1.86
I 1/2 4 1/2 15.27 0.60 47.97 1.89
J 4 5/8 15.4 0.61 48.38 1.9
J 1/4 4 3/4 15.53 0.61 48.79 1.92
J 1/2 5 15.7 0.62 49.32 1.94
K 5 1/8 15.8 0.62 49.64 1.95
K 1/4 5 1/4 15.9 0.63 49.95 1.97
K 1/2 5 3/8 16 0.63 50.27 1.98
L 5 1/2 16.1 0.63 50.58 1.99
L 1/4 5 3/4 16.3 0.64 51.21 2.02
L 1/2 5 7/8 16.41 0.65 51.55 2.03
M 6 16.51 0.65 51.87 2.04
M 1/2 6 1/4 16.71 0.66 52.5 2.07
N 6 1/2 16.92 0.67 53.16 2.09
N 1/2 6 3/4 17.13 0.67 53.82 2.12
O 7 17.35 0.68 54.51 2.15
O 1/2 7 1/4 17.45 0.69 54.82 2.16
P 7 1/2 17.75 0.70 55.76 2.2
P 1/2 7 3/4 17.97 0.71 56.45 2.22
Q 8 18.19 0.72 57.15 2.25
Q 1/2 8 1/4 18.35 0.72 57.65 2.27
Q 3/4 8 1/2 18.53 0.73 58.21 2.29
R 8 5/8 18.61 0.73 58.47 2.3
R 1/4 8 3/4 18.69 0.74 58.72 2.31
R 1/2 8 7/8 18.8 0.74 59.06 2.32
R 3/4 9 18.89 0.75 59.34 2.35
S 9 1/8 19.1 0.75 60 2.36
S 1/4 9 1/4 19.22 0.76 60.38 2.38
S 1/2 9 3/8 19.31 0.76 60.66 2.39
S 3/4 9 1/2 19.41 0.76 60.98 2.4
T 9 5/8 19.51 0.77 61.29 2.41
T 1/4 9 3/4 19.62 0.77 61.64 2.43
T 1/2 10 19.84 0.78 62.33 2.45
U 10 1/4 20.02 0.79 62.89 2.48
U 1/2 10 1/2 20.2 0.80 63.46 2.5
V 10 5/8 20.32 0.80 63.84 2.51
V 1/4 10 3/4 20.44 0.81 64.21 2.53
V 1/2 11 20.68 0.81 64.97 2.56
W 11 1/8 20.76 0.82 65.22 2.57
W 1/4 11 1/4 20.85 0.82 65.5 2.58
W 1/2 11 3/8 20.94 0.82 65.78 2.59
W 3/4 11 1/2 21.08 0.83 66.22 2.61
X 11 5/8 21.18 0.83 66.54 2.62
X 1/4 11 3/4 21.24 0.84 66.73 2.63
X 1/2 11 7/8 21.3 0.84 66.92 2.64
Y 12 21.49 0.85 67.51 2.66
Y 1/2 12 1/4 21.69 0.85 68.14 2.68
Z 12 1/2 21.89 0.86 68.77 2.71