Conversion · United Kingdom to Switzerland

UK / Australia to Swiss ring sizes.

UK / Australia M½ = Swiss 13 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	Swiss	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	0	12.62 mm	39.7 mm
C½	0	12.83 mm	40.3 mm
D	1	13.03 mm	40.9 mm
D½	2	13.23 mm	41.6 mm
E	2	13.44 mm	42.2 mm
E½	3	13.64 mm	42.8 mm
F	3	13.84 mm	43.5 mm
F½	4	14.05 mm	44.1 mm
G	5	14.25 mm	44.8 mm
G½	5	14.45 mm	45.4 mm
H	6	14.66 mm	46.0 mm
H½	7	14.86 mm	46.7 mm
I	7	15.06 mm	47.3 mm
I½	8	15.27 mm	48.0 mm
J	9	15.47 mm	48.6 mm
J½	9	15.67 mm	49.2 mm
K	10	15.88 mm	49.9 mm
K½	11	16.08 mm	50.5 mm
L	11	16.28 mm	51.2 mm
L½	12	16.49 mm	51.8 mm
M	12	16.69 mm	52.4 mm
M½	13	16.89 mm	53.1 mm
N	14	17.10 mm	53.7 mm
N½	14	17.30 mm	54.3 mm
O	15	17.50 mm	55.0 mm
O½	16	17.71 mm	55.6 mm
P	16	17.91 mm	56.3 mm
P½	17	18.11 mm	56.9 mm
Q	18	18.32 mm	57.5 mm
Q½	18	18.52 mm	58.2 mm
R	19	18.72 mm	58.8 mm
R½	19	18.93 mm	59.5 mm
S	20	19.13 mm	60.1 mm
S½	21	19.33 mm	60.7 mm
T	21	19.54 mm	61.4 mm
T½	22	19.74 mm	62.0 mm
U	23	19.94 mm	62.7 mm
U½	23	20.15 mm	63.3 mm
V	24	20.35 mm	63.9 mm
V½	25	20.55 mm	64.6 mm
W	25	20.76 mm	65.2 mm
W½	26	20.96 mm	65.8 mm
X	26	21.16 mm	66.5 mm
X½	27	21.37 mm	67.1 mm
Y	outside range	21.57 mm	67.8 mm
Y½	outside range	21.77 mm	68.4 mm
Z	outside range	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 →