Ring Size Converter

Convert between US, UK, EU, Indian, and Japanese ring sizes instantly.

From

Full Conversion Table

US	UK	EU	India	Japan	Ø mm	C mm
3	F	44	3	4	14.05	44.2
3.5	G	45.5	4	5	14.45	45.4
4	H	46.8	5	7	14.86	46.7
4.5	I	48	6	8	15.27	47.9
5	J½	49.3	8	9	15.7	49.3
5.5	K½	50.6	9	10	16.1	50.6
6	L½	51.9	10	12	16.51	51.9
6.5	M½	53.1	11	13	16.92	53.1
7	N½	54.4	13	14	17.35	54.5
7.5	O½	55.7	14	15	17.75	55.8
8	P½	57	15	16	18.19	57.2
8.5	Q½	58.3	17	17	18.53	58.2
9	R½	59.5	18	18	18.89	59.3
9.5	S½	60.8	19	19	19.41	61
10	T½	62.1	20	20	19.84	62.3
10.5	U½	63.4	21	21	20.2	63.5
11	V½	64.6	22	22	20.68	64.9
11.5	W½	65.9	23	23	21.08	66.2
12	X½	67.2	25	25	21.49	67.5
12.5	Z	68.5	26	26	21.89	68.8
13	Z+1	69.7	27	27	22.33	70.1

Understanding Ring Size Conversion

Ring size conversion can be confusing because every country uses a different scale. The US and Canada use a numerical system (3–13 with half sizes), while the UK, Australia, and South Africa use letters (A–Z). The EU system directly reflects the inner circumference in millimeters, making it the most measurement-friendly standard. India uses a numbered scale (1–30), and Japan follows the JIS standard with its own numbered system that is not interchangeable with Indian sizes.

To convert accurately, you need to match the inner diameter or circumference of the ring across systems. For example, a ring size mm to US conversion of 17.3 mm diameter equals approximately US 7. Converting India ring size to US requires a lookup table since the scales are not proportional — Indian size 12 corresponds to approximately US 6.5, while Indian size 16 maps to about US 8.5. Similarly, Japan ring size to US conversion is non-linear: Japanese size 9 equals roughly US 5. Australian and New Zealand sizes follow the UK letter system, so ring size AU to US conversion uses the same UK-to-US mapping.

Use the converter above for instant cross-system translation, or explore our complete ring size chart for a side-by-side reference. If you don't know your size at all, start with our free ring size calculator.