Please find here all the info to measure your ring size. The chart below shows different methods of measuring your ring size.

Italian size	Inside diameter (mm)	Inside circumference (mm)	German size	French size	UK size	US size
4	14,00 - 14,10	44,00 - 44,3	44	44	F	3
5	14,20 - 14,40	44,60 - 45,20	45	45	F	3
6	14,50 - 14,70	45,60 - 46,20	46	46	G	3,5
7	14,80 - 15,10	46,50 - 47,40	47	47	H	4
8	15,20 - 15,40	47,80 - 48,40	48	48	I	4,5
9	15,50 - 15,70	48,70 - 49,30	49	49	J	5
10	15,80 - 16,00	49,60 - 50,30	50	50	K	5
11	16,10 - 16,30	50,60 - 51,20	51	51	L	5,5
12	16,40 - 16,60	51,50 - 52,20	52	52	L	6
13	16,70 - 17,00	52,50 - 53,40	53	53	M	6
14	17,10 - 17,30	53,70 - 54,30	54	54	N	6,5
15	17,40 - 17,60	54,70 - 55,30	55	55	O	7
16	17,70 - 17,90	55,60 - 56,20	56	56	O	7,5
17	18,00 - 18,20	56,50 - 57,20	57	57	P	8
18	18,30 - 18,60	57,50 - 58,40	58	58	Q	8,5
19	18,70 - 18,90	58,70 - 59,40	59	59	R	8,5
20	19,00 - 19,20	59,70 - 60,30	60	60	S	9
21	19,30 - 19,50	60,60 - 61,30	61	61	S	9
22	19,60 - 19,80	61,60 - 62,20	62	62	T	9,5
23	19,90 - 20,10	62,50 - 63,10	63	63	U	10
24	20,20 - 20,50	63,50 - 64,40	64	64	V	n.d.
25	20,60 - 20,80	64,70 - 65,30	65	65	V	10,5
26	20,90 - 21,10	65,70 - 66,30	66	66	W	11
27	21,20 - 21,50	66,30 - 67,50	67	67	X	11,5
28	21,60 - 21,80	67,90 - 68,50	68	68	Y	12
29	21,90 - 22,10	68,80 - 69,40	69	69	Z	12,5
30	22,20 - 22,40	69,70 - 70,40	70	70	Z	13
31	22,50 - 22,70	70,70 - 71,30	71	71	Z	13