Free tool

Ring Size Converter

Convert between US, UK, European, Japanese, and metric ring sizes instantly. Includes a full reference chart and instructions for measuring at home.

Size system

Ring size

Reference chart

US	UK	EU	JP	mm ⌀
1	B	41	1	12.95
1.5	C	42	2	13.26
2	D	42.5	3	13.56
2.5	E	43.5	4	13.87
3	F	44	5	14.17
3.5	G	45	6	14.48
4	H	46	7	14.78
4.5	I	47	8	15.09
5	J	48	9	15.40
5.5	K	49	10	15.70
6	L	50	11	16.01
6.5	M	51	12	16.31
7	N	52	13	16.62
7.5	O	53	14	16.92
8	P	54	15	17.23
8.5	Q	55	16	17.53
9	R	56	17	17.84
9.5	S	57	18	18.14
10	T	58	19	18.45
10.5	U	59	20	18.76
11	V	60	21	19.06
11.5	W	61	22	19.37
12	X	62	23	19.68
12.5	Y	63	24	19.98
13	Z	64	25	20.29
13.5	Z+1	65	26	20.60
14	Z+2	66	27	20.90
14.5	Z+3	67	28	21.21
15	Z+4	68	29	21.51
15.5	Z+5	69	30	21.82
16	Z+6	70	31	22.12

How to measure your ring size at home

Cut a thin strip of paper or use a piece of string, about 10 cm long.
Wrap it snugly around the base of the finger you want to measure.
Mark where the strip overlaps, then lay it flat and measure the length in millimeters.
Enter the circumference above and select "Circumference (mm)" as the system.

Tip: Measure at the end of the day when fingers are slightly larger. Avoid measuring when very cold or very hot.

About this tool

Ring sizes vary significantly across countries. The US and Canada use a numeric system (1–16 with half sizes), the UK and Australia use letters (A–Z+), Europe uses circumference in millimeters, and Japan uses its own numeric scale.

This converter maps all major systems using standardized diameter and circumference measurements. Note that there are minor variations between standards, and ring width can affect the perceived fit — wider bands typically require a half size up.

Related resources

Ring production and sizing guide Jewelry pricing calculator Diamond price estimator

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Download our complete ring sizing reference with printable size strips included.