Conversion · United Kingdom to United States

UK / Australia to US / Canada ring sizes.

UK / Australia M½ = US / Canada 6½ 16.89 mm across · 53.1 mm around

Both scales describe the same physical ring. The table below converts every size in the range, derived from inner circumference rather than copied.

UK / Australia	US / Canada	Diameter	Circumference
A	outside range	11.81 mm	37.1 mm
A½	outside range	12.01 mm	37.7 mm
B	outside range	12.22 mm	38.4 mm
B½	outside range	12.42 mm	39.0 mm
C	outside range	12.62 mm	39.7 mm
C½	outside range	12.83 mm	40.3 mm
D	outside range	13.03 mm	40.9 mm
D½	outside range	13.23 mm	41.6 mm
E	outside range	13.44 mm	42.2 mm
E½	outside range	13.64 mm	42.8 mm
F	outside range	13.84 mm	43.5 mm
F½	3	14.05 mm	44.1 mm
G	3	14.25 mm	44.8 mm
G½	3½	14.45 mm	45.4 mm
H	3½	14.66 mm	46.0 mm
H½	4	14.86 mm	46.7 mm
I	4	15.06 mm	47.3 mm
I½	4½	15.27 mm	48.0 mm
J	4½	15.47 mm	48.6 mm
J½	5	15.67 mm	49.2 mm
K	5	15.88 mm	49.9 mm
K½	5½	16.08 mm	50.5 mm
L	5½	16.28 mm	51.2 mm
L½	6	16.49 mm	51.8 mm
M	6	16.69 mm	52.4 mm
M½	6½	16.89 mm	53.1 mm
N	6½	17.10 mm	53.7 mm
N½	7	17.30 mm	54.3 mm
O	7	17.50 mm	55.0 mm
O½	7½	17.71 mm	55.6 mm
P	8	17.91 mm	56.3 mm
P½	8	18.11 mm	56.9 mm
Q	8½	18.32 mm	57.5 mm
Q½	8½	18.52 mm	58.2 mm
R	9	18.72 mm	58.8 mm
R½	9	18.93 mm	59.5 mm
S	9½	19.13 mm	60.1 mm
S½	9½	19.33 mm	60.7 mm
T	10	19.54 mm	61.4 mm
T½	10	19.74 mm	62.0 mm
U	10½	19.94 mm	62.7 mm
U½	10½	20.15 mm	63.3 mm
V	11	20.35 mm	63.9 mm
V½	11	20.55 mm	64.6 mm
W	11½	20.76 mm	65.2 mm
W½	11½	20.96 mm	65.8 mm
X	12	21.16 mm	66.5 mm
X½	12	21.37 mm	67.1 mm
Y	12½	21.57 mm	67.8 mm
Y½	12½	21.77 mm	68.4 mm
Z	13	21.98 mm	69.0 mm

Measure in the evening — fingers swell through the day and in heat — and let your jeweller's own chart take precedence over this one. How to measure at home →