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UK ring sizes to US

Every UK, Irish and Australian ring size from A to Z+6, in half letters, with its US and Canadian size, its EU and Japanese size and the inside measurements. Type a letter to convert it.

A size 9 ring is R½ in letters, and UK N is US 6.75: each letter is about half a US size.

US / Canada: 6.75
UK / Australia: N
EU / ISO 8653: 54
Japan: 13
Inside diameter: 17.11 mm
Inside circumference: 53.75 mm (5.38 cm)

US to the nearest quarter and EU to the nearest half size, as Design Facts reports them in the studio.

UK to US ring size chart

Each row is a UK letter, with ½ for the half size above it. US sizes are to the nearest quarter and EU sizes to the nearest half, as Design Facts reports them; the ring size converter lists US sizes in order and converts centimetres.

UK and Australian letter ring sizes with US, EU and Japanese sizes and inside diameter and circumference
UK / Australia	US / Canada	EU / ISO	Japan	Diameter mm	Circumference mm
A	0.5	37.5	—	11.94	37.50
A½	0.5	38	—	12.14	38.13
B	0.75	39	—	12.33	38.75
B½	1	39.5	—	12.53	39.38
C	1.25	40	—	12.73	40.00
C½	1.5	40.5	1	12.93	40.63
D	1.75	41.5	1	13.13	41.25
D½	2	42	2	13.33	41.88
E	2.25	42.5	3	13.53	42.50
E½	2.5	43	3	13.73	43.13
F	2.75	44	4	13.93	43.75
F½	3	44.5	4	14.13	44.38
G	3.25	45	5	14.32	45.00
G½	3.5	45.5	6	14.52	45.63
H	3.75	46.5	6	14.72	46.25
H½	4	47	7	14.92	46.88
I	4.25	47.5	7	15.12	47.50
I½	4.5	48	8	15.32	48.13
J	4.75	49	9	15.52	48.75
J½	5	49.5	9	15.72	49.38
K	5.25	50	10	15.92	50.00
K½	5.5	50.5	10	16.11	50.63
L	5.75	51.5	11	16.31	51.25
L½	6	52	12	16.51	51.88
M	6.25	52.5	12	16.71	52.50
M½	6.5	53	13	16.91	53.13
N	6.75	54	13	17.11	53.75
N½	7	54.5	14	17.31	54.38
O	7.25	55	15	17.51	55.00
O½	7.5	55.5	15	17.71	55.63
P	7.75	56.5	16	17.90	56.25
P½	8	57	16	18.10	56.88
Q	8.25	57.5	17	18.30	57.50
Q½	8.5	58	18	18.50	58.13
R	8.75	59	18	18.70	58.75
R½	9	59.5	19	18.90	59.37
S	9.25	60	19	19.10	60.00
S½	9.5	60.5	20	19.30	60.63
T	9.75	61.5	20	19.50	61.25
T½	10	62	21	19.70	61.88
U	10.25	62.5	22	19.89	62.50
U½	10.5	63	22	20.09	63.13
V	10.75	63.5	23	20.29	63.75
V½	11	64.5	23	20.49	64.38
W	11.25	65	24	20.69	65.00
W½	11.5	65.5	25	20.89	65.63
X	11.75	66.5	25	21.09	66.25
X½	12	67	26	21.29	66.88
Y	12.25	67.5	26	21.49	67.50
Y½	12.25	68	27	21.68	68.13
Z	12.5	69	28	21.88	68.75
Z½	12.75	69.5	28	22.08	69.38
Z+1	13	70	29	22.28	70.00
Z+1½	13.25	70.5	29	22.48	70.63
Z+2	13.5	71.5	30	22.68	71.25
Z+2½	13.75	72	31	22.88	71.88
Z+3	14	72.5	31	23.08	72.50
Z+3½	14.25	73	32	23.28	73.13
Z+4	14.5	74	32	23.48	73.75
Z+4½	14.75	74.5	33	23.67	74.38
Z+5	15	75	34	23.87	75.00
Z+5½	15.25	75.5	34	24.07	75.63
Z+6	15.5	76.5	35	24.27	76.25

Common questions

What is a size 9 ring in letters?

R½. US 9 is 18.95 mm across the inside and 59.52 mm round, which is R½ in UK, Irish and Australian sizes. US 7 is N½, US 8 is P½ and US 10 is T½.

How do I convert an English ring size to US?

Find the letter in the chart: the US size is beside it. Each letter adds 1.25 mm of inside circumference, about half a US size, so L is US 5.75, M is US 6.25, N is US 6.75 and P is US 7.75. In the converter, type the letter with ½ for a half size, such as N½.

Are UK, Irish and Australian ring sizes the same?

Yes. All three use the letters of British Standard BS 6820, which start with A at 37.5 mm of inside circumference and add 1.25 mm a letter, with half sizes between.

What comes after size Z?

Z½, then Z+1, Z+1½ and on in the same steps up to Z+6, which is US 15.5 and 24.27 mm across the inside.

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