United Kingdom · 51 sizes

UK / Australia Ring Size Chart.

Letters A to Z with half sizes. Also used in Ireland, Australia and New Zealand.

Every row is computed from inner circumference, so the diameter and the equivalents in other systems are consistent all the way down.

UK / Australia	Diameter	Circumference	Indian	US / Canada	EU / ISO 8653	Japan / China	Swiss
A	11.81 mm	37.1 mm	—	—	—	—	—
A½	12.01 mm	37.7 mm	—	—	—	—	—
B	12.22 mm	38.4 mm	—	—	—	—	—
B½	12.42 mm	39.0 mm	—	—	—	—	—
C	12.62 mm	39.7 mm	—	—	—	—	0
C½	12.83 mm	40.3 mm	—	—	—	—	0
D	13.03 mm	40.9 mm	—	—	—	1	1
D½	13.23 mm	41.6 mm	1	—	—	2	2
E	13.44 mm	42.2 mm	1	—	—	3	2
E½	13.64 mm	42.8 mm	2	—	—	3	3
F	13.84 mm	43.5 mm	3	—	—	4	3
F½	14.05 mm	44.1 mm	4	3	44	5	4
G	14.25 mm	44.8 mm	4	3	45	5	5
G½	14.45 mm	45.4 mm	5	3½	45	6	5
H	14.66 mm	46.0 mm	6	3½	46	7	6
H½	14.86 mm	46.7 mm	7	4	47	7	7
I	15.06 mm	47.3 mm	7	4	47	8	7
I½	15.27 mm	48.0 mm	8	4½	48	9	8
J	15.47 mm	48.6 mm	9	4½	49	9	9
J½	15.67 mm	49.2 mm	9	5	49	10	9
K	15.88 mm	49.9 mm	10	5	50	11	10
K½	16.08 mm	50.5 mm	11	5½	51	12	11
L	16.28 mm	51.2 mm	12	5½	51	12	11
L½	16.49 mm	51.8 mm	12	6	52	13	12
M	16.69 mm	52.4 mm	13	6	52	14	12
M½	16.89 mm	53.1 mm	14	6½	53	14	13
N	17.10 mm	53.7 mm	14	6½	54	15	14
N½	17.30 mm	54.3 mm	15	7	54	16	14
O	17.50 mm	55.0 mm	16	7	55	16	15
O½	17.71 mm	55.6 mm	17	7½	56	17	16
P	17.91 mm	56.3 mm	17	8	56	18	16
P½	18.11 mm	56.9 mm	18	8	57	19	17
Q	18.32 mm	57.5 mm	19	8½	58	19	18
Q½	18.52 mm	58.2 mm	19	8½	58	20	18
R	18.72 mm	58.8 mm	20	9	59	21	19
R½	18.93 mm	59.5 mm	21	9	59	21	19
S	19.13 mm	60.1 mm	22	9½	60	22	20
S½	19.33 mm	60.7 mm	22	9½	61	23	21
T	19.54 mm	61.4 mm	23	10	61	23	21
T½	19.74 mm	62.0 mm	24	10	62	24	22
U	19.94 mm	62.7 mm	25	10½	63	25	23
U½	20.15 mm	63.3 mm	25	10½	63	26	23
V	20.35 mm	63.9 mm	26	11	64	26	24
V½	20.55 mm	64.6 mm	27	11	65	27	25
W	20.76 mm	65.2 mm	27	11½	65	—	25
W½	20.96 mm	65.8 mm	28	11½	66	—	26
X	21.16 mm	66.5 mm	29	12	66	—	26
X½	21.37 mm	67.1 mm	30	12	67	—	27
Y	21.57 mm	67.8 mm	30	12½	68	—	—
Y½	21.77 mm	68.4 mm	—	12½	68	—	—
Z	21.98 mm	69.0 mm	—	13	—	—	—

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A jeweller's own chart takes precedence over this one — makers differ by a fraction of a size and a proper mandrel beats a paper strip. Fingers also swell through the day and in heat, so measure in the evening. How to measure at home →